Yellowstone National Park
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Yellowstone National Park is an American national park located in the
western United States The Western United States (also called the American West, the Far West, and the West) is the region comprising the westernmost states of the United States. As American settlement in the U.S. expanded westward, the meaning of the term ''the We ...
, largely in the northwest corner of
Wyoming Wyoming () is a U.S. state, state in the Mountain states, Mountain West subregion of the Western United States. It is bordered by Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho to the west, Utah to the south ...
and extending into
Montana Montana () is a state in the Mountain West division of the Western United States. It is bordered by Idaho to the west, North Dakota and South Dakota to the east, Wyoming to the south, and the Canadian provinces of Alberta, British Columbi ...
and
Idaho Idaho ( ) is a state in the Pacific Northwest region of the Western United States. To the north, it shares a small portion of the Canada–United States border with the province of British Columbia. It borders the states of Montana and Wyomi ...
. It was established by the 42nd U.S. Congress with the
Yellowstone National Park Protection Act The Yellowstone National Park Protection Act was a law passed by the 42nd US Congress and signed into law by President Ulysses S. Grant on March 1, 1872, creating Yellowstone National Park Yellowstone National Park is an American national ...
and signed into law by
President Ulysses S. Grant Ulysses S. Grant (born Hiram Ulysses Grant ; April 27, 1822July 23, 1885) was an American military officer and politician who served as the 18th president of the United States from 1869 to 1877. As Commanding General, he led the Union Ar ...
on March 1, 1872. Yellowstone was the first national park in the U.S. and is also widely held to be the first national park in the world. The park is known for its wildlife and its many geothermal features, especially the
Old Faithful Old Faithful is a cone geyser in Yellowstone National Park in Wyoming, United States. It was named in 1870 during the Washburn–Langford–Doane Expedition and was the first geyser in the park to be named. It is a highly predictable geotherm ...
geyser, one of its most popular. While it represents many types of
biome A biome () is a biogeographical unit consisting of a biological community that has formed in response to the physical environment in which they are found and a shared regional climate. Biomes may span more than one continent. Biome is a broader ...
s, the
subalpine Montane ecosystems are found on the slopes of mountains. The alpine climate in these regions strongly affects the ecosystem because temperatures fall as elevation increases, causing the ecosystem to stratify. This stratification is a crucial f ...
forest is the most abundant. It is part of the
South Central Rockies forests The South Central Rockies forests is a temperate coniferous forest ecoregion of the United States located mainly in Wyoming, Idaho, and Montana. It has a considerably drier climate than the North Central Rockies forest. Setting This ecoregion i ...
ecoregion An ecoregion (ecological region) or ecozone (ecological zone) is an ecologically and geographically defined area that is smaller than a bioregion, which in turn is smaller than a biogeographic realm. Ecoregions cover relatively large areas of l ...
. While Native Americans have lived in the Yellowstone region for at least 11,000 years, aside from visits by
mountain men A mountain man is an explorer who lives in the wilderness. Mountain men were most common in the North American Rocky Mountains from about 1810 through to the 1880s (with a peak population in the early 1840s). They were instrumental in opening up ...
during the early-to-mid-19th century, organized exploration did not begin until the late 1860s. Management and control of the park originally fell under the jurisdiction of the
United States Department of the Interior The United States Department of the Interior (DOI) is one of the executive departments of the U.S. federal government headquartered at the Main Interior Building, located at 1849 C Street NW in Washington, D.C. It is responsible for the ma ...
, the first
Secretary of the Interior Secretary of the Interior may refer to: * Secretary of the Interior (Mexico) * Interior Secretary of Pakistan * Secretary of the Interior and Local Government (Philippines) * United States Secretary of the Interior See also

*Interior ministry ...
to supervise the park being
Columbus Delano Columbus Delano (June 4, 1809 – October 23, 1896) was a lawyer, rancher, banker, statesman, and a member of the prominent Delano family. Forced to live on his own at an early age, Delano struggled to become a self-made man. Delano was electe ...
. However, the U.S. Army was eventually commissioned to oversee management of Yellowstone for a 30-year period between 1886 and 1916. In 1917, administration of the park was transferred to the
National Park Service The National Park Service (NPS) is an agency of the United States federal government within the U.S. Department of the Interior that manages all national parks, most national monuments, and other natural, historical, and recreational propert ...
, which had been created the previous year. Hundreds of structures have been built and are protected for their architectural and
historical significance Historical significance is a historiographical key concept that explores and seeks to explain the selection of particular social and cultural past events for remembrance by human societies. This element of selection involved in both ascribing and ...
, and researchers have examined more than a thousand
archaeological site An archaeological site is a place (or group of physical sites) in which evidence of past activity is preserved (either prehistoric or historic or contemporary), and which has been, or may be, investigated using the discipline of archaeology a ...
s. Yellowstone National Park spans an area of , comprising lakes, canyons, rivers, and
mountain range A mountain range or hill range is a series of mountains or hills arranged in a line and connected by high ground. A mountain system or mountain belt is a group of mountain ranges with similarity in form, structure, and alignment that have arise ...
s.
Yellowstone Lake Yellowstone Lake is the largest body of water in Yellowstone National Park. The lake is above sea level and covers with of shoreline. While the average depth of the lake is , its greatest depth is at least . Yellowstone Lake is the largest fre ...
is one of the largest high-elevation lakes in North America and is centered over the
Yellowstone Caldera The Yellowstone Caldera, sometimes referred to as the Yellowstone Supervolcano, is a volcanic caldera and supervolcano in Yellowstone National Park in the Western United States. The caldera and most of the park are located in the northwest corn ...
, the largest supervolcano on the continent. The
caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is ...
is considered a
dormant volcano A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates a ...
. It has erupted with tremendous force several times in the last two million years. Well over half of the world's geysers and hydrothermal features are in Yellowstone, fueled by this ongoing volcanism.
Lava Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or un ...
flows and rocks from volcanic eruptions cover most of the land area of Yellowstone. The park is the centerpiece of the
Greater Yellowstone Ecosystem The Greater Yellowstone Ecosystem (GYE) is one of the last remaining large, nearly intact ecosystems in the northern temperate zone of the Earth. It is located within the northern Rocky Mountains, in areas of northwestern Wyoming, southwestern M ...
, the largest remaining nearly-intact ecosystem in the Earth's northern temperate zone. In 1978, Yellowstone was named a
UNESCO World Heritage Site A World Heritage Site is a landmark or area with legal protection by an international convention administered by the United Nations Educational, Scientific and Cultural Organization (UNESCO). World Heritage Sites are designated by UNESCO for ...
. Hundreds of species of mammals, birds, fish, reptiles, and amphibians have been documented, including several that are either
endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and in ...
or
threatened Threatened species are any species (including animals, plants and fungi) which are vulnerable to endangerment in the near future. Species that are threatened are sometimes characterised by the population dynamics measure of ''critical depensa ...
. The vast forests and grasslands also include unique species of plants. Yellowstone Park is the largest, and most famous megafauna location in the contiguous United States. Grizzly bears,
wolves The wolf (''Canis lupus''; : wolves), also known as the gray wolf or grey wolf, is a large canine native to Eurasia and North America. More than thirty subspecies of ''Canis lupus'' have been recognized, and gray wolves, as popularly un ...
, and free-ranging herds of bison and
elk The elk (''Cervus canadensis''), also known as the wapiti, is one of the largest species within the deer family, Cervidae, and one of the largest terrestrial mammals in its native range of North America and Central and East Asia. The common ...
live in this park. The
Yellowstone Park bison herd The Yellowstone Park bison herd is a bison herd in Yellowstone National Park. It is probably the oldest and largest public bison herd in the United States, estimated in 2020 to be 4,800 bison. The bison in the Yellowstone Park bison herd are Am ...
is the oldest and largest public bison herd in the United States. Forest fires occur in the park each year; in the large forest fires of 1988, nearly one third of the park was burnt. Yellowstone has numerous recreational opportunities, including hiking,
camping Camping is an outdoor activity involving overnight stays away from home, either without shelter or using basic shelter such as a tent, or a recreational vehicle. Typically, participants leave developed areas to spend time outdoors in more na ...
, boating, fishing, and sightseeing. Paved roads provide close access to the major geothermal areas as well as some of the lakes and waterfalls. During the winter, visitors often access the park by way of guided tours that use either
snow coach A snow coach is a specialized passenger transport vehicle designed to operate over snow or ice, similar to a large, multi-passenger snowcat that is equipped with bus-style seating. These vehicles may have multiple sets of very large, low-pressur ...
es or
snowmobile A snowmobile, also known as a Ski-Doo, snowmachine, sled, motor sled, motor sledge, skimobile, or snow scooter, is a motorized vehicle designed for winter travel and recreation on snow. It is designed to be operated on snow and ice and does not ...
s.


History

The park contains the headwaters of the
Yellowstone River The Yellowstone River is a tributary of the Missouri River, approximately long, in the Western United States. Considered the principal tributary of upper Missouri, via its own tributaries it drains an area with headwaters across the mountains a ...
, from which it takes its historical name. Near the end of the 18th century, French trappers named the river ', which is probably a translation of the
Hidatsa The Hidatsa are a Siouan people. They are enrolled in the federally recognized Three Affiliated Tribes of the Fort Berthold Reservation in North Dakota. Their language is related to that of the Crow, and they are sometimes considered a parent ...
name ' ("Yellow Stone River"). Later, American trappers rendered the French name in English as "Yellow Stone". Although it is commonly believed that the river was named for the yellow rocks seen in the
Grand Canyon of the Yellowstone The Grand Canyon of the Yellowstone is the first large canyon on the Yellowstone River downstream from Yellowstone Falls in Yellowstone National Park in Wyoming. The canyon is approximately long, between deep and from wide. History Althoug ...
, the Native American name source is unclear. The human history of the park began at least 11,000 years ago when Native Americans began to hunt and fish in the region. During the construction of the post office in
Gardiner, Montana Gardiner is a unincorporated community in Park County, Montana, United States, along the 45th parallel. As of the 2020 census, the population of the community and nearby areas was 833. Gardiner was officially founded in 1880. The area has s ...
, in the 1950s, an obsidian point of Clovis origin was found that dated from approximately 11,000 years ago. These Paleo-Indians, of the Clovis culture, used the significant amounts of obsidian found in the park to make cutting tools and weapons.
Arrowhead An arrowhead or point is the usually sharpened and hardened tip of an arrow, which contributes a majority of the projectile mass and is responsible for impacting and penetrating a target, as well as to fulfill some special purposes such as sign ...
s made of Yellowstone obsidian have been found as far away as the
Mississippi Valley The Mississippi River is the second-longest river and chief river of the second-largest drainage system in North America, second only to the Hudson Bay drainage system. From its traditional source of Lake Itasca in northern Minnesota, it ...
, indicating that a regular obsidian trade existed between local tribes and tribes farther east. When the
Lewis and Clark Expedition The Lewis and Clark Expedition, also known as the Corps of Discovery Expedition, was the United States expedition to cross the newly acquired western portion of the country after the Louisiana Purchase. The Corps of Discovery was a select gr ...
entered present-day Montana in 1805 they encountered the
Nez Perce The Nez Percé (; autonym in Nez Perce language: , meaning "we, the people") are an Indigenous people of the Plateau who are presumed to have lived on the Columbia River Plateau in the Pacific Northwest region for at least 11,500 years.Ames, K ...
,
Crow A crow is a bird of the genus '' Corvus'', or more broadly a synonym for all of ''Corvus''. Crows are generally black in colour. The word "crow" is used as part of the common name of many species. The related term "raven" is not pinned scientifica ...
, and Shoshone tribes who described to them the Yellowstone region to the south, but they chose not to investigate. In 1806,
John Colter John Colter (c.1770–1775 – May 7, 1812 or November 22, 1813) was a member of the Lewis and Clark Expedition (1804–1806). Though party to one of the more famous expeditions in history, Colter is best remembered for explorations he made ...
, a member of the
Lewis and Clark Expedition The Lewis and Clark Expedition, also known as the Corps of Discovery Expedition, was the United States expedition to cross the newly acquired western portion of the country after the Louisiana Purchase. The Corps of Discovery was a select gr ...
, left to join a group of
fur trappers The fur trade is a worldwide industry dealing in the acquisition and sale of animal fur. Since the establishment of a world fur market in the early modern period, furs of boreal, polar and cold temperate mammalian animals have been the most ...
. After splitting up with the other trappers in 1807, Colter passed through a portion of what later became the park, during the winter of 1807–1808. He observed at least one geothermal area in the northeastern section of the park, near
Tower Fall Tower Fall is a waterfall on Tower Creek in the northeastern region of Yellowstone National Park, in the U.S. state of Wyoming. Approximately upstream from the creek's confluence with the Yellowstone River, the fall plunges 132 feet (40&nbs ...
. After surviving wounds he suffered in a battle with members of the Crow and Blackfoot tribes in 1809, Colter described a place of "
fire and brimstone Fire and brimstone ( ''gofrit va’esh'', grc, πυρὸς καὶ θείου) is an idiomatic expression referring to God's wrath found in both the Hebrew Bible and the Christian New Testament. In the Bible, it often appears in reference t ...
" that most people dismissed as delirium; the supposedly mystical place was nicknamed "
Colter's Hell Colter's Hell is an area of fumaroles and hot springs on the Shoshone River near Cody in the U.S. state of Wyoming. The thermal area covers about at the mouth of the Shoshone's canyon. Its thermal activity has declined since its description by ...
". Over the next 40 years, numerous reports from mountain men and trappers told of boiling mud, steaming rivers, and
petrified In geology, petrifaction or petrification () is the process by which organic material becomes a fossil through the replacement of the original material and the filling of the original pore spaces with minerals. Petrified wood typifies this proce ...
trees, yet most of these reports were believed at the time to be myth. After an 1856 exploration, mountain man
Jim Bridger James Felix "Jim" Bridger (March 17, 1804 – July 17, 1881) was an American mountain man, trapper, Army scout, and wilderness guide who explored and trapped in the Western United States in the first half of the 19th century. He was known as Old ...
(also believed to be the first or second European American to have seen the Great Salt Lake) reported observing boiling springs, spouting water, and a mountain of glass and yellow rock. These reports were largely ignored because Bridger was a known "spinner of yarns". In 1859, a U.S. Army Surveyor named Captain William F. Raynolds embarked on a two-year survey of the southern central Rockies. After wintering in Wyoming, in May 1860, Raynolds and his party—which included geologist Ferdinand V. Hayden and guide Jim Bridger—attempted to cross the Continental Divide over Two Ocean Plateau from the Wind River drainage in northwest Wyoming. Heavy spring snows prevented their passage, but had they been able to traverse the divide, the party would have been the first organized survey to enter the Yellowstone region. The
American Civil War The American Civil War (April 12, 1861 – May 26, 1865; also known by other names) was a civil war in the United States. It was fought between the Union ("the North") and the Confederacy ("the South"), the latter formed by states th ...
hampered further organized explorations until the late 1860s. The first detailed expedition to the Yellowstone area was the
Cook–Folsom–Peterson Expedition The Cook–Folsom–Peterson Expedition of 1869 was the first organized expedition to explore the region that became Yellowstone National Park. The privately financed expedition was carried out by David E. Folsom, Charles W. Cook and William Pete ...
of 1869, which consisted of three privately funded explorers. The Folsom party followed the Yellowstone River to Yellowstone Lake. The members of the Folsom party kept a journal, and based on the information it reported, a party of Montana residents organized the
Washburn–Langford–Doane Expedition The Washburn Expedition of 1870 explored the region of northwestern Wyoming that two years later became Yellowstone National Park. Led by Henry D. Washburn and Nathaniel P. Langford, and with a U.S. Army escort headed by Lt. Gustavus C. Doane, ...
in 1870. It was headed by the surveyor-general of Montana Henry Washburn, and included Nathaniel P. Langford (who later became known as "National Park" Langford) and a U.S. Army detachment commanded by Lt.  Gustavus Doane. The expedition spent about a month exploring the region, collecting specimens and naming sites of interest. A Montana writer and lawyer named Cornelius Hedges, who had been a member of the Washburn expedition, proposed that the region should be set aside and protected as a national park; he wrote detailed articles about his observations for the ''Helena Herald'' newspaper between 1870 and 1871. Hedges essentially restated comments made in October 1865 by acting Montana Territorial Governor
Thomas Francis Meagher Thomas Francis Meagher (; 3 August 18231 July 1867) was an Irish nationalist and leader of the Young Irelanders in the Rebellion of 1848. After being convicted of sedition, he was first sentenced to death, but received transportation for life ...
, who had previously commented that the region should be protected. Others made similar suggestions. An 1871 letter to Ferdinand V. Hayden from
Jay Cooke Jay Cooke (August 10, 1821 – February 16, 1905) was an American financier who helped finance the Union war effort during the American Civil War and the postwar development of railroads in the northwestern United States. He is generally acknowle ...
, a businessman who wanted to bring tourists to the region, encouraged him to mention it in his official report of the survey. Cooke wrote that his friend, Congressman William D. Kelley had also suggested "
Congress A congress is a formal meeting of the representatives of different countries, constituent states, organizations, trade unions, political parties, or other groups. The term originated in Late Middle English to denote an encounter (meeting of ...
pass a bill reserving the Great Geyser Basin as a public park forever".


Park creation

In 1871, eleven years after his failed first effort, Ferdinand V. Hayden was finally able to explore the region. With government sponsorship, he returned to the region with a second, larger expedition, the
Hayden Geological Survey of 1871 The Hayden Geological Survey of 1871 explored the region of northwestern Wyoming that later became Yellowstone National Park in 1872. It was led by geologist Ferdinand Vandeveer Hayden. The 1871 survey was not Hayden's first, but it was the first ...
. He compiled a comprehensive report, including large-format photographs by
William Henry Jackson William Henry Jackson (April 4, 1843 – June 30, 1942) was an American photographer, Civil War veteran, painter, and an explorer famous for his images of the American West. He was a great-great nephew of Samuel Wilson, the progenitor of Am ...
and paintings by
Thomas Moran Thomas Moran (February 12, 1837 – August 25, 1926) was an American painter and printmaker of the Hudson River School in New York whose work often featured the Rocky Mountains. Moran and his family, wife Mary Nimmo Moran and daughter Ruth too ...
. The report helped to convince the U.S. Congress to withdraw this region from public auction. On March 1, 1872, President
Ulysses S. Grant Ulysses S. Grant (born Hiram Ulysses Grant ; April 27, 1822July 23, 1885) was an American military officer and politician who served as the 18th president of the United States from 1869 to 1877. As Commanding General, he led the Union Ar ...
signed ''The Act of Dedication'' law that created Yellowstone National Park. Hayden, while not the only person to have thought of creating a park in the region, was its first and most enthusiastic advocate. He believed in "setting aside the area as a pleasure ground for the benefit and enjoyment of the people" and warned that there were those who would come and "make merchandise of these beautiful specimens". Worrying the area could face the same fate as
Niagara Falls Niagara Falls () is a group of three waterfalls at the southern end of Niagara Gorge, spanning the border between the province of Ontario in Canada and the state of New York in the United States. The largest of the three is Horseshoe Fall ...
, he concluded the site should "be as free as the air or Water." In his report to the Committee on Public Lands, he concluded that if the bill failed to become law, "the vandals who are now waiting to enter into this wonder-land, will in a single season despoil, beyond recovery, these remarkable curiosities, which have required all the cunning skill of nature thousands of years to prepare". Hayden and his 1871 party recognized Yellowstone as a unique place that should be available for further research. He also was encouraged to preserve it for others to see and experience it as well. In 1873, Congress authorized and funded a survey to find a wagon route to the park from the south which was completed by the Jones Expedition of 1873. Eventually the railroads and, some time after that, the automobile would make that possible. The park was not set aside strictly for ecological purposes; however, the designation "pleasure ground" was not an invitation to create an amusement park. Hayden imagined something akin to the scenic resorts and baths in England, Germany, and Switzerland. There was considerable local opposition to the Yellowstone National Park during its early years. Some of the locals feared that the regional economy would be unable to thrive if there remained strict federal prohibitions against resource development or settlement within park boundaries and local entrepreneurs advocated reducing the size of the park so that mining, hunting, and logging activities could be developed. To this end, numerous bills were introduced into Congress by Montana representatives who sought to remove the federal land-use restrictions. After the park's official formation, Nathaniel Langford was appointed as the park's first superintendent in 1872 by Secretary of Interior
Columbus Delano Columbus Delano (June 4, 1809 – October 23, 1896) was a lawyer, rancher, banker, statesman, and a member of the prominent Delano family. Forced to live on his own at an early age, Delano struggled to become a self-made man. Delano was electe ...
, the first overseer and controller of the park. Langford served for five years but was denied a salary, funding, and staff. Langford lacked the means to improve the land or properly protect the park, and without formal policy or regulations, he had few legal methods to enforce such protection. This left Yellowstone vulnerable to
poachers Poaching has been defined as the illegal hunting or capturing of wild animals, usually associated with land use rights. Poaching was once performed by impoverished peasants for subsistence purposes and to supplement meager diets. It was set a ...
,
vandals The Vandals were a Germanic people who first inhabited what is now southern Poland. They established Vandal kingdoms on the Iberian Peninsula, Mediterranean islands, and North Africa in the fifth century. The Vandals migrated to the area betw ...
, and others seeking to raid its resources. He addressed the practical problems park administrators faced in the 1872 Report to the Secretary of the Interior and correctly predicted that Yellowstone would become a major international attraction deserving the continuing stewardship of the government. In 1874, both Langford and Delano advocated the creation of a federal agency to protect the vast park, but Congress refused. In 1875, Colonel
William Ludlow William Ludlow (November 27, 1843 – August 30, 1901) was an officer in the Corps of Engineers and a major general in the United States Army who served in the Civil War, Plains Indian Wars, the Spanish–American War, and led a scientific exped ...
, who had previously explored areas of Montana under the command of
George Armstrong Custer George Armstrong Custer (December 5, 1839 – June 25, 1876) was a United States Army officer and cavalry commander in the American Civil War and the American Indian Wars. Custer graduated from West Point in 1861 at the bottom of his class, b ...
, was assigned to organize and lead an expedition to Montana and the newly established Yellowstone Park. Observations about the lawlessness and exploitation of park resources were included in Ludlow's ''Report of a Reconnaissance to the Yellowstone National Park''. The report included letters and attachments by other expedition members, including naturalist and mineralogist
George Bird Grinnell George Bird Grinnell (September 20, 1849 – April 11, 1938) was an American anthropologist, historian, naturalist, and writer. Grinnell was born in Brooklyn, New York, and graduated from Yale University with a B.A. in 1870 and a Ph.D. in 1880. ...
. Grinnell documented the
poaching Poaching has been defined as the illegal hunting or capturing of wild animals, usually associated with land use rights. Poaching was once performed by impoverished peasants for subsistence purposes and to supplement meager diets. It was set a ...
of buffalo,
deer Deer or true deer are hoofed ruminant mammals forming the family Cervidae. The two main groups of deer are the Cervinae, including the muntjac, the elk (wapiti), the red deer, and the fallow deer; and the Capreolinae, including the re ...
,
elk The elk (''Cervus canadensis''), also known as the wapiti, is one of the largest species within the deer family, Cervidae, and one of the largest terrestrial mammals in its native range of North America and Central and East Asia. The common ...
, and antelope for hides. "It is estimated that during the winter of 1874–1875, not less than 3,000 buffalo and mule deer suffer even more severely than the elk, and the antelope nearly as much." As a result, Langford was forced to step down in 1877. Having traveled through Yellowstone and witnessed land management problems first hand,
Philetus Norris Philetus W. Norris (August 17, 1821 – January 14, 1885) was the second superintendent of Yellowstone National Park and was the first person to be paid for that position. Early life Philetus Walter Norris was born in Palmyra, New York on Aug ...
volunteered for the position following Langford's exit. Congress finally saw fit to implement a salary for the position, as well as to provide minimal funding to operate the park. Norris used these funds to expand access to the park, building numerous crude roads and facilities. In 1880,
Harry Yount Henry S. Yount (March 18, 1839May 16, 1924) was an American Civil War soldier, mountain man, professional hunter and trapper, prospector, wilderness guide and packer, seasonal employee of the United States Department of the Interior, and ...
was appointed as a gamekeeper to control poaching and vandalism in the park. Yount had previously spent decades exploring the mountain country of present-day Wyoming, including the Grand Tetons, after joining F V. Hayden's Geological Survey in 1873. Yount is the first national park ranger, and Yount's Peak, at the head of the Yellowstone River, was named in his honor. However, these measures still proved to be insufficient in protecting the park, as neither Norris, nor the three superintendents who followed, were given sufficient manpower or resources. The
Northern Pacific Railroad The Northern Pacific Railway was a transcontinental railroad that operated across the northern tier of the western United States, from Minnesota to the Pacific Northwest. It was approved by Congress in 1864 and given nearly of land grants, whi ...
built a train station in
Livingston, Montana Livingston is a city and county seat of Park County, Montana, United States. It is in southwestern Montana, on the Yellowstone River, north of Yellowstone National Park. As of the 2020 census, the population of the city was 8,040. History T ...
, connecting to the northern entrance in the early 1880s, which helped to increase visitation from 300 in 1872 to 5,000 in 1883. A line was also extended from Livingston to Gardiner station, where passengers switched to stagecoach. Visitors in these early years faced poor roads and limited services, and most access into the park was on horse or via stagecoach. By 1908 visitation increased enough to attract a
Union Pacific Railroad The Union Pacific Railroad , legally Union Pacific Railroad Company and often called simply Union Pacific, is a freight-hauling railroad that operates 8,300 locomotives over routes in 23 U.S. states west of Chicago and New Orleans. Union Paci ...
connection to West Yellowstone, though rail visitation fell off considerably by
World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...
and ceased around the 1960s. Much of the railroad line was converted to nature trails, among them the Yellowstone Branch Line Trail. During the 1870s and 1880s, Native American tribes were effectively excluded from the national park. Under a half-dozen tribes had made seasonal use of the Yellowstone area- the only year-round residents were small bands of
Eastern Shoshone Eastern Shoshone are Shoshone who primarily live in Wyoming and in the northeast corner of the Great Basin where Utah, Idaho and Wyoming meet and are in the Great Basin classification of Indigenous People. They lived in the Rocky Mountains d ...
known as " Sheepeaters". They left the area under the assurances of a treaty negotiated in 1868, under which the Sheepeaters ceded their lands but retained the right to hunt in Yellowstone. The United States never ratified the treaty, and refused to recognize the claims of the Sheepeaters or any other tribe that had used Yellowstone. The
Nez Perce The Nez Percé (; autonym in Nez Perce language: , meaning "we, the people") are an Indigenous people of the Plateau who are presumed to have lived on the Columbia River Plateau in the Pacific Northwest region for at least 11,500 years.Ames, K ...
band associated with
Chief Joseph ''Hin-mah-too-yah-lat-kekt'' (or ''Hinmatóowyalahtq̓it'' in Americanist orthography), popularly known as Chief Joseph, Young Joseph, or Joseph the Younger (March 3, 1840 – September 21, 1904), was a leader of the Wal-lam-wat-kain (Wallowa ...
, numbering about 750 people, passed through Yellowstone National Park in thirteen days during late August 1877. They were being pursued by the U.S. Army and entered the national park about two weeks after the
Battle of the Big Hole The Battle of the Big Hole was fought in Montana Territory, August 9–10, 1877, between the United States Army and the Nez Perce tribe of Native Americans during the Nez Perce War. Both sides suffered heavy casualties. The Nez Perce withd ...
. Some of the Nez Perce were friendly to the tourists and other people they encountered in the park; some were not. Nine park visitors were briefly taken captive. Despite Joseph and other chiefs ordering that no one should be harmed, at least two people were killed and several wounded. One of the areas where encounters occurred was in Lower Geyser Basin and east along a branch of the
Firehole River The Firehole River is located in northwestern Wyoming, and is one of the two major tributaries of the Madison River. It flows north approximately from its source in Madison Lake on the Continental Divide to join the Gibbon River at Madison Junc ...
to Mary Mountain and beyond. That stream is still known as Nez Perce Creek. A group of
Bannocks The Bannock tribe were originally Northern Paiute but are more culturally affiliated with the Northern Shoshone. They are in the Great Basin classification of Indigenous People. Their traditional lands include northern Nevada, southeastern Oreg ...
entered the park in 1878, alarming park Superintendent
Philetus Norris Philetus W. Norris (August 17, 1821 – January 14, 1885) was the second superintendent of Yellowstone National Park and was the first person to be paid for that position. Early life Philetus Walter Norris was born in Palmyra, New York on Aug ...
. In the aftermath of the
Sheepeater Indian War The Big Horned Sheepeater Indian War of 1879 was the last Indian war fought in the Pacific Northwest portion of the United States; it took place primarily in central Idaho. A high mountain band of approximately 300 Shoshone people, the Tukudeka, ...
of 1879, Norris built a fort to prevent Native Americans from entering the national park. Ongoing poaching and destruction of natural resources continued unabated until the U.S. Army arrived at
Mammoth Hot Springs Mammoth Hot Springs is a large complex of hot springs on a hill of travertine in Yellowstone National Park adjacent to Fort Yellowstone and the Mammoth Hot Springs Historic District. It was created over thousands of years as hot water from the ...
in 1886 and built Camp Sheridan. Over the next 22 years, as the army constructed permanent structures, Camp Sheridan was renamed
Fort Yellowstone Fort Yellowstone was a U.S. Army fort, established in 1891 at Mammoth Hot Springs in Yellowstone National Park. Yellowstone was designated in 1872 but the Interior Department was unable to effectively manage the park. Administration was transfer ...
. On May 7, 1894, the
Boone and Crockett Club The Boone and Crockett Club is an American nonprofit organization that advocates fair chase hunting in support of habitat conservation. The club is North America's oldest wildlife and habitat conservation organization, founded in the United Sta ...
, acting through the personality of George G. Vest, Arnold Hague, William Hallett Phillips, W. A. Wadsworth, Archibald Rogers,
Theodore Roosevelt Theodore Roosevelt Jr. ( ; October 27, 1858 – January 6, 1919), often referred to as Teddy or by his initials, T. R., was an American politician, statesman, soldier, conservationist, naturalist, historian, and writer who served as the 26t ...
, and
George Bird Grinnell George Bird Grinnell (September 20, 1849 – April 11, 1938) was an American anthropologist, historian, naturalist, and writer. Grinnell was born in Brooklyn, New York, and graduated from Yale University with a B.A. in 1870 and a Ph.D. in 1880. ...
were successful in carrying through the Park Protection Act, which saved the park. The
Lacey Act of 1900 The Lacey Act of 1900 is a conservation law in the United States that prohibits trade in wildlife, fish, and plants that have been illegally taken, possessed, transported, or sold.United States. Lacey Act (Game). , ch. 553. Approved May 25, 1900. ...
provided legal support for the officials prosecuting poachers. With the funding and manpower necessary to keep a diligent watch, the army developed their own policies and regulations that permitted public access while protecting park wildlife and natural resources. When the National Park Service was created in 1916, many of the management principles developed by the army were adopted by the new agency. The army turned control over to the National Park Service on October 31, 1918. In 1898, the naturalist
John Muir John Muir ( ; April 21, 1838December 24, 1914), also known as "John of the Mountains" and "Father of the National Parks", was an influential Scottish-American naturalist, author, environmental philosopher, botanist, zoologist, glaciologist ...
described the park as follows: "However orderly your excursions or aimless, again and again amid the calmest, stillest scenery you will be brought to a standstill hushed and awe-stricken before phenomena wholly new to you. Boiling springs and huge deep pools of purest green and azure water, thousands of them, are plashing and heaving in these high, cool mountains as if a fierce furnace fire were burning beneath each one of them; and a hundred geysers, white torrents of boiling water and steam, like inverted waterfalls, are ever and anon rushing up out of the hot, black underworld."


Later history

By 1915, 1,000 automobiles per year were entering the park, resulting in conflicts with horses and horse-drawn transportation. Horse travel on roads was eventually prohibited. The
Civilian Conservation Corps The Civilian Conservation Corps (CCC) was a voluntary government work relief program that ran from 1933 to 1942 in the United States for unemployed, unmarried men ages 18–25 and eventually expanded to ages 17–28. The CCC was a major part of ...
(CCC), a New Deal relief agency for young men, played a major role between 1933 and 1942 in developing Yellowstone facilities. CCC projects included reforestation, campground development of many of the park's trails and campgrounds, trail construction, fire hazard reduction, and fire-fighting work. The CCC built the majority of the early visitor centers, campgrounds and the current system of park roads. During
World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposi ...
, tourist travel fell sharply, staffing was cut, and many facilities fell into disrepair. By the 1950s, visitation increased tremendously in Yellowstone and other national parks. To accommodate the increased visitation, park officials implemented Mission 66, an effort to modernize and expand park service facilities. Planned to be completed by 1966, in honor of the 50th anniversary of the founding of the National Park Service, Mission 66 construction diverged from the traditional log cabin style with design features of a modern style. During the late 1980s, most construction styles in Yellowstone reverted to the more traditional designs. After the enormous forest fires of 1988 damaged much of
Grant Village Grant Village is a developed area of Yellowstone National Park, offering lodging, camping and other visitor services. It is located on the southwest side of Yellowstone Lake, about south of West Thumb Geyser Basin. Grant Village was developed by ...
, structures there were rebuilt in the traditional style. The visitor center at Canyon Village, which opened in 2006, incorporates a more traditional design as well. The 1959 Hebgen Lake earthquake just west of Yellowstone at
Hebgen Lake Hebgen Lake is a reservoir created by the Hebgen Dam, located in Gallatin County in southwest Montana. It is well known for the 1959 Hebgen Lake earthquake (magnitude 7.1 to 7.5) which occurred nearby on August 17, 1959, forming Quake Lake, whic ...
damaged roads and some structures in the park. In the northwest section of the park, new geysers were found, and many existing hot springs became turbid. It was the most powerful earthquake to hit the region in recorded history. In 1963, after several years of public controversy regarding the forced reduction of the elk population in Yellowstone, United States Secretary of the Interior Stewart Udall appointed an advisory board to collect scientific data to inform future wildlife management of the national parks. In a paper known as the
Leopold Report The Leopold Report, officially known as Wildlife Management in the National Parks, is a 1963 paper composed of a series of ecosystem management recommendations that were presented by the Special Advisory Board on Wildlife Management to United St ...
, the committee observed that culling programs at other national parks had been ineffective, and recommended management of Yellowstone's elk population. The
wildfire A wildfire, forest fire, bushfire, wildland fire or rural fire is an unplanned, uncontrolled and unpredictable fire in an area of Combustibility and flammability, combustible vegetation. Depending on the type of vegetation present, a wildfire ...
s during the summer of 1988 were the largest in the history of the park. Approximately or 36% of the parkland was impacted by the fires, leading to a systematic re-evaluation of fire management policies. The fire season of 1988 was considered normal until a combination of drought and heat by mid-July contributed to an extreme fire danger. On " Black Saturday", August 20, 1988, strong winds expanded the fires rapidly, and more than burned. The expansive cultural history of the park has been documented by the 1,000 archeological sites that have been discovered. The park has 1,106 historic structures and features, and of these Obsidian Cliff and five buildings have been designated
National Historic Landmarks A National Historic Landmark (NHL) is a building, district, object, site, or structure that is officially recognized by the United States government for its outstanding historical significance. Only some 2,500 (~3%) of over 90,000 places listed ...
. Yellowstone was designated an
International Biosphere Reserve Man and the Biosphere Programme (MAB) is an intergovernmental scientific program, launched in 1971 by UNESCO, that aims to establish a scientific basis for the improvement of relationships between people and their environments. MAB's work engag ...
on October 26, 1976, and a UN
World Heritage Site A World Heritage Site is a landmark or area with legal protection by an international convention administered by the United Nations Educational, Scientific and Cultural Organization (UNESCO). World Heritage Sites are designated by UNESCO for h ...
on September 8, 1978. The park was placed on the
List of World Heritage in Danger The List of World Heritage in Danger is compiled by the United Nations Educational, Scientific and Cultural Organization (UNESCO) through the World Heritage Committee according to Article 11.4 of the World Heritage Convention,Full title: ''Conv ...
from 1995 to 2003 due to the effects of tourism, infection of wildlife, and issues with invasive species. In 2010, Yellowstone National Park was honored with its own
quarter A quarter is one-fourth, , 25% or 0.25. Quarter or quarters may refer to: Places * Quarter (urban subdivision), a section or area, usually of a town Placenames * Quarter, South Lanarkshire, a settlement in Scotland * Le Quartier, a settlement ...
under the America the Beautiful Quarters Program. Justin Ferrell explores three moral sensibilities that motivated activists in dealing with Yellowstone. First came the utilitarian vision of maximum
exploitation of natural resources The exploitation of natural resources is the use of natural resources for economic growth, sometimes with a negative connotation of accompanying environmental degradation. It started to emerge on an industrial scale in the 19th century as the e ...
, characteristic of developers in the late 19th century. Second was the spiritual vision of nature inspired by the Romanticism and the transcendentalists in the mid-19th century. The twentieth century saw the biocentric moral vision that focuses on the health of the ecosystem as theorized by Aldo Leopold, which led to the expansion of federally protected areas and to the surrounding ecosystems.


Heritage and Research Center

The Heritage and Research Center is located at
Gardiner, Montana Gardiner is a unincorporated community in Park County, Montana, United States, along the 45th parallel. As of the 2020 census, the population of the community and nearby areas was 833. Gardiner was officially founded in 1880. The area has s ...
, near the north entrance to the park. The center is home to the Yellowstone National Park's museum collection, archives, research library, historian, archeology lab, and herbarium. The Yellowstone National Park Archives maintain collections of historical records of Yellowstone and the National Park Service. The collection includes the administrative records of Yellowstone, as well as resource management records, records from major projects, and donated manuscripts and personal papers. The archives are affiliated with the
National Archives and Records Administration The National Archives and Records Administration (NARA) is an " independent federal agency of the United States government within the executive branch", charged with the preservation and documentation of government and historical records. It ...
.


Geography

Approximately 96 percent of the land area of Yellowstone National Park is located within the state of Wyoming. Another three percent is within Montana, with the remaining one percent in Idaho. The park is north to south, and west to east by air. Yellowstone is in area, larger than either of the states of
Rhode Island Rhode Island (, like ''road'') is a state in the New England region of the Northeastern United States. It is the smallest U.S. state by area and the seventh-least populous, with slightly fewer than 1.1 million residents as of 2020, but it ...
or
Delaware Delaware ( ) is a state in the Mid-Atlantic region of the United States, bordering Maryland to its south and west; Pennsylvania to its north; and New Jersey and the Atlantic Ocean to its east. The state takes its name from the adjacent Del ...
. Rivers and lakes cover five percent of the land area, with the largest water body being
Yellowstone Lake Yellowstone Lake is the largest body of water in Yellowstone National Park. The lake is above sea level and covers with of shoreline. While the average depth of the lake is , its greatest depth is at least . Yellowstone Lake is the largest fre ...
at . Yellowstone Lake is up to deep and has of shoreline. At an elevation of above sea level, Yellowstone Lake is the largest high elevation lake in North America. Forests comprise 80 percent of the land area of the park; most of the rest is
grassland A grassland is an area where the vegetation is dominated by grasses (Poaceae). However, sedge (Cyperaceae) and rush (Juncaceae) can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur natur ...
. The Continental Divide of North America runs diagonally through the southwestern part of the park. The divide is a
topographic Topography is the study of the forms and features of land surfaces. The topography of an area may refer to the land forms and features themselves, or a description or depiction in maps. Topography is a field of geoscience and planetary scien ...
feature that separates Pacific Ocean and Atlantic Ocean water drainages. About one third of the park lies on the west side of the divide. The origins of the
Yellowstone Yellowstone National Park is an American national park located in the western United States, largely in the northwest corner of Wyoming and extending into Montana and Idaho. It was established by the 42nd U.S. Congress with the Yellowston ...
and Snake Rivers are near each other but on opposite sides of the divide. As a result, the waters of the Snake River flow to the Pacific Ocean, while those of the Yellowstone find their way to the
Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an oceanic basin, ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of ...
. The park sits on the
Yellowstone Plateau The Yellowstone Plateau Volcanic Field, also known as the Yellowstone Supervolcano or the Yellowstone Volcano, is a complex volcano, volcanic plateau and volcanic field located mostly in the western U.S. state of Wyoming but also stretches into I ...
, at an average elevation of above sea level. The plateau is bounded on nearly all sides by
mountain range A mountain range or hill range is a series of mountains or hills arranged in a line and connected by high ground. A mountain system or mountain belt is a group of mountain ranges with similarity in form, structure, and alignment that have arise ...
s of the Middle Rocky Mountains, which range from in elevation. The highest point in the park is atop
Eagle Peak Eagle Peak is the name of 44 mountain peaks of the United States including: *Eagle Peak (Alaska) * Eagle Peak (Admiralty Island), in Alaska * Eagle Peak (Washington), a summit in Mount Rainier National Park *Eagle Peak (Mariposa County, California), ...
() and the lowest is along Reese Creek (). Nearby mountain ranges include the
Gallatin Range The Gallatin Range is a mountain range of the Rocky Mountains, located in the U.S. states of Montana and Wyoming. It includes more than 10 mountains over . The highest peak in the range is Electric Peak at . The Gallatin Range was named after ...
to the northwest, the
Beartooth Mountains The Beartooth Mountains are located in south central Montana and northwest Wyoming, U.S. and are part of the Absaroka-Beartooth Wilderness, within Custer, Gallatin and Shoshone National Forests. The Beartooths are the location of Granite Peak, ...
in the north, the
Absaroka Range The Absaroka Range ( or ) is a sub- range of the Rocky Mountains in the United States. The range stretches about across the Montana–Wyoming border, and at its widest, forming the eastern boundary of Yellowstone National Park along Paradise V ...
to the east, the
Teton Range The Teton Range is a mountain range of the Rocky Mountains in North America. It extends for approximately in a north–south direction through the U.S. state of Wyoming, east of the Idaho state line. It is south of Yellowstone National Park and ...
to the south, and the
Madison Range The Madison Range is a mountain range located in the Rocky Mountains of Montana and Idaho in the United States. The range was named in honor of future President of the United States, then U.S. Secretary of State James Madison by Meriwether Lewis ...
to the west. The most prominent summit on the Yellowstone Plateau is
Mount Washburn Mount Washburn, elevation , is a prominent mountain peak in the Washburn Range in Yellowstone National Park, Wyoming. The peak was named in 1870 to honor Henry D. Washburn, leader of the Washburn–Langford–Doane Expedition. The Washburn Range ...
at . Yellowstone National Park has one of the world's largest
petrified forests Petrified wood, also known as petrified tree (from Ancient Greek meaning 'rock' or 'stone'; literally 'wood turned into stone'), is the name given to a special type of '' fossilized wood'', the fossilized remains of terrestrial vegetation. ' ...
, trees which were long ago buried by ash and soil and transformed from wood to mineral materials. This ash and other volcanic debris are believed to have come from the park area itself as the central part of Yellowstone is the massive caldera of a supervolcano. The park contains 290
waterfall A waterfall is a point in a river or stream where water flows over a vertical drop or a series of steep drops. Waterfalls also occur where meltwater drops over the edge of a tabular iceberg or ice shelf. Waterfalls can be formed in severa ...
s of at least , the highest being the Lower Falls of the Yellowstone River at . Three deep canyons are located in the park, cut through the
volcanic tuff Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is lithified into a solid rock. Rock that contains greater than 75% ash is considered tuff, while rock cont ...
of the Yellowstone Plateau by rivers over the last 640,000 years. The Lewis River flows through
Lewis Canyon The Lewis River is an U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map, accessed May 4, 2011 tributary of the Snake River. The entire course of the river is located within the boundaries of Yellows ...
in the south, and the
Yellowstone River The Yellowstone River is a tributary of the Missouri River, approximately long, in the Western United States. Considered the principal tributary of upper Missouri, via its own tributaries it drains an area with headwaters across the mountains a ...
has carved two colorful canyons, the
Grand Canyon of the Yellowstone The Grand Canyon of the Yellowstone is the first large canyon on the Yellowstone River downstream from Yellowstone Falls in Yellowstone National Park in Wyoming. The canyon is approximately long, between deep and from wide. History Althoug ...
and the Black Canyon of the Yellowstone in its journey north.


Geology


Volcanism

Yellowstone is at the northeastern end of the Snake River Plain, a great U-shaped arc through the mountains that extends from
Boise, Idaho Boise (, , ) is the capital and most populous city of the U.S. state of Idaho and is the county seat of Ada County. On the Boise River in southwestern Idaho, it is east of the Oregon border and north of the Nevada border. The downtown ar ...
some to the west. The volcanism of Yellowstone is believed to be linked to the somewhat older volcanism of Snake River plain. Yellowstone is thus the active part of a hotspot that has moved northeast over time. The origin of this hotspot volcanism is disputed. One theory holds that a
mantle plume A mantle plume is a proposed mechanism of convection within the Earth's mantle, hypothesized to explain anomalous volcanism. Because the plume head partially melts on reaching shallow depths, a plume is often invoked as the cause of volcanic hot ...
has caused the
Yellowstone hotspot The Yellowstone hotspot is a volcanic hotspot in the United States responsible for large scale volcanism in Idaho, Montana, Nevada, Oregon, and Wyoming, formed as the North American tectonic plate moved over it. It formed the eastern Snake Ri ...
to migrate northeast, while another theory explains migrating hotspot volcanism as the result of the fragmentation and dynamics of the
subducted Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, the ...
Farallon Plate The Farallon Plate was an ancient oceanic plate. It formed one of the three main plates of Panthalassa, alongside the Phoenix Plate and Izanagi Plate, which were connected by a triple junction. The Farallon Plate began subducting under the west ...
in Earth's interior. The
Yellowstone Caldera The Yellowstone Caldera, sometimes referred to as the Yellowstone Supervolcano, is a volcanic caldera and supervolcano in Yellowstone National Park in the Western United States. The caldera and most of the park are located in the northwest corn ...
is the largest volcanic system in North America, and worldwide it is only rivaled by the
Lake Toba Caldera Lake Toba ( id, Danau Toba) ( Toba Batak: ᯖᯀᯬ ᯖᯬᯅ; romanized: ''Tao Toba'') is a large natural lake in North Sumatra, Indonesia, occupying the caldera of a supervolcano. The lake is located in the middle of the northern part of th ...
on
Sumatra Sumatra is one of the Sunda Islands of western Indonesia. It is the largest island that is fully within Indonesian territory, as well as the sixth-largest island in the world at 473,481 km2 (182,812 mi.2), not including adjacent i ...
. It has been termed a " supervolcano" because the caldera was formed by exceptionally large explosive eruptions. The
magma chamber A magma chamber is a large pool of liquid rock beneath the surface of the Earth. The molten rock, or magma, in such a chamber is less dense than the surrounding country rock, which produces buoyant forces on the magma that tend to drive it up ...
that lies under Yellowstone is estimated to be a single connected chamber, about long, wide, and 3 to 7 miles (5 to 12 km) deep. The current
caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is ...
was created by a cataclysmic eruption that occurred 640,000 years ago, which released more than 240 cubic miles (1,000 km³) of ash, rock and
pyroclast Tephra is fragmental material produced by a volcanic eruption regardless of composition, fragment size, or emplacement mechanism. Volcanologists also refer to airborne fragments as pyroclasts. Once clasts have fallen to the ground, they rem ...
ic materials./ This eruption was more than 1,000 times larger than the 1980 eruption of Mount St. Helens. It produced a caldera nearly 5/8 of a mile (1 km) deep and in area and deposited the
Lava Creek Tuff The Lava Creek Tuff is a tuff formation in Wyoming, Montana and Idaho, United States, created during the Lava Creek eruption around 630,000 years ago, which formed the Yellowstone Caldera. The Lava Creek Tuff is distributed in a radial pattern ar ...
, a
welded tuff Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is lithified into a solid rock. Rock that contains greater than 75% ash is considered tuff, while rock cont ...
geologic formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exp ...
. The most violent known eruption, which occurred 2.1 million years ago, ejected 588 cubic miles (2,450 km³) of volcanic material and created the rock formation known as the
Huckleberry Ridge Tuff The Huckleberry Ridge Tuff is a tuff formation created by the Huckleberry Ridge eruption that formed the Island Park Caldera that lies partially in Yellowstone National Park, Wyoming and stretches westward into Idaho into a region known as Island ...
and created the
Island Park Caldera The Island Park Caldera, in the U.S. states of Idaho and Wyoming, is one of the world's largest calderas, with approximate dimensions of 80 by 65 km. Its ashfall is the source of the Huckleberry Ridge Tuff that is found from southern Calif ...
. A smaller eruption ejected 67 cubic miles (280 km³) of material 1.3 million years ago, forming the
Henry's Fork Caldera The Henry's Fork Caldera in eastern Idaho is a caldera located in an area known as Island Park, west of Yellowstone National Park. The caldera was formed by an eruption 1.3 million years ago of the Yellowstone hotspot. The eruption distributed ...
and depositing the Mesa Falls Tuff. Each of the three climactic eruptions released vast amounts of ash that blanketed much of central North America, falling many hundreds of miles away. The amount of ash and gases released into the atmosphere probably caused significant impacts to world weather patterns and led to the
extinction Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...
of some species, primarily in North America. A subsequent caldera-forming eruption occurred about 160,000 years ago. It formed the relatively small caldera that contains the West Thumb of Yellowstone Lake. Since the last supereruption, a series of smaller eruptive cycles between 640,000 and 70,000 years ago, has nearly filled in the Yellowstone Caldera with 80 different eruptions of
rhyolitic Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained groundmass. The mineral ...
lavas such as those that can be seen at Obsidian Cliffs and
basalt Basalt (; ) is an aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the surface of a rocky planet or moon. More than 90 ...
ic lavas which can be viewed at Sheepeater Cliff. Lava strata are most easily seen at the Grand Canyon of the Yellowstone, where the Yellowstone River continues to carve into the ancient lava flows. The canyon is a classic
V-shaped valley A valley is an elongated low area often running between hills or mountains, which will typically contain a river or stream running from one end to the other. Most valleys are formed by erosion of the land surface by rivers or streams over ...
, indicative of river-type erosion rather than erosion caused by
glaciation A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate be ...
. Each eruption is part of an eruptive cycle that climaxes with the partial collapse of the roof of the volcano's partially emptied magma chamber. This creates a collapsed depression, called a caldera, and releases vast amounts of volcanic material, usually through fissures that ring the caldera. The time between the last three cataclysmic eruptions in the Yellowstone area has ranged from 600,000 to 800,000 years, but the small number of such climactic eruptions cannot be used to make an accurate prediction for future volcanic events.


Geysers and the hydrothermal system

The most famous geyser in the park, and perhaps the world, is
Old Faithful Old Faithful is a cone geyser in Yellowstone National Park in Wyoming, United States. It was named in 1870 during the Washburn–Langford–Doane Expedition and was the first geyser in the park to be named. It is a highly predictable geotherm ...
geyser, located in
Upper Geyser Basin The geothermal areas of Yellowstone include several geyser basins in Yellowstone National Park as well as other geothermal features such as hot springs, mud pots, and fumaroles. The number of thermal features in Yellowstone is estimated at 10, ...
.
Castle Geyser Castle Geyser is a cone geyser in the Upper Geyser Basin of Yellowstone National Park. It is noted for the particularly large geyserite sinter deposits, which form its cone. These deposits have been likened in appearance to a castle. When the ...
, Lion Geyser,
Beehive Geyser Beehive Geyser is a geyser in the Upper Geyser Basin of Yellowstone National Park in the United States. The tall cone resembles a straw beehive. Beehive's Indicator is a small, jagged cone-type geyser located about from Beehive. History On Sep ...
,
Grand Geyser Grand Geyser is a fountain geyser in the Upper Geyser Basin of Yellowstone National Park in the United States. It is the tallest predictable geyser known. It was named by Ferdinand Vandeveer Hayden Ferdinand Vandeveer Hayden (September 7, ...
(the world's tallest predictable geyser),
Giant Geyser Giant Geyser is a cone-type geyser in the Upper Geyser Basin of Yellowstone National Park in the United States. Giant Geyser is the namesake for the Giant Group of geysers, which, on its platform, includes Bijou Geyser, Catfish Geyser, Mastiff Ge ...
(the world's most voluminous geyser),
Riverside Geyser Riverside Geyser is a geyser in Yellowstone National Park in the U.S. state of Wyoming. The geyser is located on the Firehole River within the Upper Geyser Basin. The geyser shoots steam and water to heights of 75 feet (23 m) in an arch over th ...
and numerous other geysers are in the same basin. The park contains the tallest active geyser in the world— Steamboat Geyser in the
Norris Geyser Basin The geothermal areas of Yellowstone include several geyser basins in Yellowstone National Park as well as other geothermal features such as hot springs, mud pots, and fumaroles. The number of thermal features in Yellowstone is estimated at ...
. A study that was completed in 2011 found that at least 1283 geysers have erupted in Yellowstone. Of these, an average of 465 are active in a given year. Yellowstone contains at least 10,000 thermal features altogether, including geysers,
hot spring A hot spring, hydrothermal spring, or geothermal spring is a spring produced by the emergence of geothermally heated groundwater onto the surface of the Earth. The groundwater is heated either by shallow bodies of magma (molten rock) or by c ...
s,
mudpot A mudpot, or mud pool, is a sort of acidic hot spring, or fumarole, with limited water. It usually takes the form of a pool of bubbling mud. The acid and microorganisms decompose surrounding rock into clay and mud. Description The mud of a mud ...
s, and
fumarole A fumarole (or fumerole) is a vent in the surface of the Earth or other rocky planet from which hot volcanic gases and vapors are emitted, without any accompanying liquids or solids. Fumaroles are characteristic of the late stages of volcani ...
s. Over half of the world's geysers and hydrothermal features are concentrated in Yellowstone. In May 2001, the
U.S. Geological Survey The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, and ...
, Yellowstone National Park, and the
University of Utah The University of Utah (U of U, UofU, or simply The U) is a public research university in Salt Lake City, Utah. It is the flagship institution of the Utah System of Higher Education. The university was established in 1850 as the University of De ...
created the Yellowstone Volcano Observatory (YVO), a partnership for long-term monitoring of the geological processes of the Yellowstone Plateau volcanic field, for disseminating information concerning the potential hazards of this geologically active region. In 2003, changes at the Norris Geyser Basin resulted in the temporary closure of some trails in the basin. New
fumarole A fumarole (or fumerole) is a vent in the surface of the Earth or other rocky planet from which hot volcanic gases and vapors are emitted, without any accompanying liquids or solids. Fumaroles are characteristic of the late stages of volcani ...
s were observed, and several geysers showed enhanced activity and increasing water temperatures. Several geysers became so hot that they were transformed into purely steaming features; the water had become superheated and they could no longer erupt normally. This coincided with the release of reports of a multiple year United States Geological Survey research project which mapped the bottom of Yellowstone Lake and identified a structural dome that had uplifted at some time in the past. Research indicated that these uplifts posed no immediate threat of a volcanic eruption, since they may have developed long ago, and there had been no temperature increase found near the uplifts. On March 10, 2004, a biologist discovered 5 dead bison which apparently had inhaled toxic geothermal gases trapped in the Norris Geyser Basin by a seasonal atmospheric inversion. This was closely followed by an upsurge of earthquake activity in April 2004. In 2006, it was reported that the Mallard Lake Dome and the Sour Creek Dome—areas that have long been known to show significant changes in their ground movement—had risen at a rate of per year from mid–2004 through 2006. As of late 2007, the uplift has continued at a reduced rate. These events inspired a great deal of media attention and speculation about the geologic future of the region. Experts responded to the conjecture by informing the public that there was no increased risk of a volcanic eruption in the near future. However, these changes demonstrate the dynamic nature of the Yellowstone hydrothermal system.


Earthquakes

Yellowstone experiences thousands of small earthquakes every year, virtually all of which are undetectable to people. There have been six earthquakes with at least
magnitude Magnitude may refer to: Mathematics *Euclidean vector, a quantity defined by both its magnitude and its direction *Magnitude (mathematics), the relative size of an object *Norm (mathematics), a term for the size or length of a vector *Order of ...
6 or greater in historical times, including the 7.2‑magnitude Hebgen Lake earthquake which occurred just outside the northwest boundary of the park in 1959. This quake triggered a huge landslide, which caused a partial dam collapse on
Hebgen Lake Hebgen Lake is a reservoir created by the Hebgen Dam, located in Gallatin County in southwest Montana. It is well known for the 1959 Hebgen Lake earthquake (magnitude 7.1 to 7.5) which occurred nearby on August 17, 1959, forming Quake Lake, whic ...
; immediately downstream, the
sediment Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sa ...
from the landslide dammed the river and created a new lake, known as
Earthquake Lake Quake Lake (officially Earthquake Lake) is a lake in the western United States, on the Madison River in southwestern Montana. It was created after an earthquake struck on August 17, 1959, with 28 fatalities. Northwest of West Yellowstone, Qu ...
. Twenty-eight people were killed, and property damage was extensive in the immediate region. The earthquake caused some geysers in the northwestern section of the park to erupt, large cracks in the ground formed and emitted steam, and some hot springs that normally have clear water turned muddy. A 6.1‑magnitude earthquake struck inside the park on June 30, 1975, but damage was minimal. For three months in 1985, 3,000 minor earthquakes were detected in the northwestern section of the park, during what has been referred to as an
earthquake swarm In seismology, an earthquake swarm is a sequence of seismic events occurring in a local area within a relatively short period. The time span used to define a swarm varies, but may be days, months, or years. Such an energy release is different f ...
, and has been attributed to minor subsidence of the Yellowstone caldera. Beginning on April 30, 2007, 16 small earthquakes with magnitudes up to 2.7 occurred in the Yellowstone Caldera for several days. These swarms of earthquakes are common, and there have been 70 such swarms between 1983 and 2008. In December 2008, over 250 earthquakes were measured over a four-day span under Yellowstone Lake, the largest measuring a magnitude of 3.9. In January 2010, more than 250 earthquakes were detected over a two-day period. Seismic activity in Yellowstone National Park continues and is reported hourly by the Earthquake Hazards Program of the U.S. Geological Survey. On March 30, 2014, a magnitude 4.8 earthquake struck almost the very middle of Yellowstone near the Norris Basin at 6:34 am; reports indicated no damage. This was the largest earthquake to hit the park since February 22, 1980.


Biology and ecology

Yellowstone National Park is the centerpiece of the Greater Yellowstone Ecosystem, a region that includes
Grand Teton National Park Grand Teton National Park is an American national park in northwestern Wyoming. At approximately , the park includes the major peaks of the Teton Range as well as most of the northern sections of the valley known as Jackson Hole. Grand Teton ...
, adjacent National Forests and expansive wilderness areas in those forests. The ecosystem is the largest remaining continuous stretch of mostly undeveloped pristine land in the contiguous United States, considered the world's largest intact ecosystem in the northern temperate zone. With the successful
wolf reintroduction Wolf reintroduction involves the reintroduction of a portion of grey wolves in areas where native wolves have been extirpated. More than 30 subspecies of ''Canis lupus'' have been recognized, and grey wolves, as colloquially understood, compris ...
program, which began in the 1990s, virtually all the original faunal species known to inhabit the region when white explorers first entered the area can be found there.


Flora

Over 1,700
species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
of trees and other
vascular plant Vascular plants (), also called tracheophytes () or collectively Tracheophyta (), form a large group of land plants ( accepted known species) that have lignified tissues (the xylem) for conducting water and minerals throughout the plant. They ...
s are native to the park. Another 170 species are considered to be
exotic species An introduced species, alien species, exotic species, adventive species, immigrant species, foreign species, non-indigenous species, or non-native species is a species living outside its native distributional range, but which has arrived there ...
and are non-native. Of the eight conifer tree species documented,
Lodgepole Pine ''Pinus contorta'', with the common names lodgepole pine and shore pine, and also known as twisted pine, and contorta pine, is a common tree in western North America. It is common near the ocean shore and in dry montane forests to the subalpin ...
forests cover 80% of the total forested areas. Other conifers, such as
Subalpine Fir ''Abies lasiocarpa'', the subalpine fir or Rocky Mountain fir, is a western North American fir tree. Description ''Abies lasiocarpa'' is a medium-sized evergreen conifer with a very narrow conic crown, growing to tall, exceptionally , with a t ...
,
Engelmann Spruce ''Picea engelmannii'', with the common names Engelmann spruce, white spruce, mountain spruce, and silver spruce, is a species of spruce native to western North America. It is mostly a high-altitude mountain tree but also appears in watered canyon ...
,
Rocky Mountain Douglas-fir ''Pseudotsuga menziesii'' var. ''glauca'', or Rocky Mountain Douglas-fir, is an evergreen conifer native to the interior mountainous regions of western North America, from central British Columbia and southwest Alberta in Canada southward through ...
and
Whitebark Pine ''Pinus albicaulis'', known by the common names whitebark pine, white bark pine, white pine, pitch pine, scrub pine, and creeping pine, is a conifer tree native to the mountains of the western United States and Canada, specifically subalpine ...
, are found in scattered groves throughout the park. As of 2007, the whitebark pine is threatened by a fungus known as
white pine blister rust ''Cronartium ribicola'' is a species of rust fungus in the family Cronartiaceae that causes the disease white pine blister rust. Other names include: (French), (German), (Spanish). ''Cronartium ribicola'' is native to China, and was subseque ...
; however, this is mostly confined to forests well to the north and west. In Yellowstone, about seven percent of the whitebark pine species have been impacted with the fungus, compared to nearly complete infestations in northwestern Montana.
Quaking Aspen ''Populus tremuloides'' is a deciduous tree native to cooler areas of North America, one of several species referred to by the common name aspen. It is commonly called quaking aspen, trembling aspen, American aspen, mountain or golden aspen, tr ...
and
willow Willows, also called sallows and osiers, from the genus ''Salix'', comprise around 400 speciesMabberley, D.J. 1997. The Plant Book, Cambridge University Press #2: Cambridge. of typically deciduous trees and shrubs, found primarily on moist s ...
s are the most common species of
deciduous In the fields of horticulture and Botany, the term ''deciduous'' () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed leaves, usually in the autumn; to the shedding of petals, ...
trees. The aspen forests have declined significantly since the early 20th century, but scientists at Oregon State University attribute recent recovery of the aspen to the
reintroduction of wolves Wolf reintroduction involves the reintroduction of a portion of gray wolf, grey wolves in areas where native wolves have been Local extinction, extirpated. More than 30 subspecies of Canis lupus, subspecies of ''Canis lupus'' have been recognized ...
which has changed the grazing habits of local elk. There are dozens of species of flowering plants that have been identified, most of which bloom between the months of May and September. The Yellowstone sand verbena is a rare flowering plant found only in Yellowstone. It is closely related to species usually found in much warmer climates, making the sand verbena an enigma. The estimated 8,000 examples of this rare flowering plant all make their home in the sandy soils on the shores of Yellowstone Lake, well above the waterline. In Yellowstone's hot waters, bacteria form mats of bizarre shapes consisting of trillions of individuals. These bacteria are some of the most primitive life forms on earth. Flies and other
arthropod Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and cuticle made of chiti ...
s live on the mats, even in the middle of the bitterly cold winters. Initially, scientists thought that microbes there gained sustenance only from
sulfur Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula ...
. In 2005 researchers from the
University of Colorado at Boulder The University of Colorado Boulder (CU Boulder, CU, or Colorado) is a public research university in Boulder, Colorado. Founded in 1876, five months before Colorado became a state, it is the flagship university of the University of Colorado sy ...
discovered that the sustenance for at least some of the diverse
hyperthermophilic A hyperthermophile is an organism that thrives in extremely hot environments—from 60 °C (140 °F) upwards. An optimal temperature for the existence of hyperthermophiles is often above 80 °C (176 °F). Hyperthermophiles are often within the doma ...
species is
molecular hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic, ...
. ''
Thermus aquaticus ''Thermus aquaticus'' is a species of bacteria that can tolerate high temperatures, one of several thermophilic bacteria that belong to the ''Deinococcota'' phylum. It is the source of the heat-resistant enzyme ''Taq'' DNA polymerase, one of th ...
'' is a Bacteria, bacterium found in the Yellowstone hot springs that produces an important enzyme (Taq polymerase) that is easily replicated in the lab and is useful in replicating DNA as part of the polymerase chain reaction (PCR) process. The retrieval of these bacteria can be achieved with no impact to the ecosystem. Other bacteria in the Yellowstone hot springs may also prove useful to scientists who are searching for cures for various diseases. In 2016, researchers from Uppsala University reported the discovery of a class of thermophiles, Hadesarchaea, in Yellowstone's Culex Basin. These organisms are capable of converting carbon monoxide and water to carbon dioxide and hydrogen. Non-native plants sometimes threaten native species by using up nutrient resources. Though exotic species are most commonly found in areas with the greatest human visitation, such as near roads and at major tourist areas, they have also spread into the backcountry. Generally, most exotic species are controlled by pulling the plants out of the soil or by spraying, both of which are time-consuming and expensive.


Fauna

Yellowstone is widely considered to be the finest megafauna wildlife habitat in the contiguous United States, lower 48 states. There are almost 60 species of mammals in the park, including the northwestern wolf, Rocky Mountain wolf, Mountain coyote, coyote, the Canada lynx, Canadian lynx, cougars, and American black bear, black and grizzly bears. Other large mammals include the bison (often referred to as buffalo),
elk The elk (''Cervus canadensis''), also known as the wapiti, is one of the largest species within the deer family, Cervidae, and one of the largest terrestrial mammals in its native range of North America and Central and East Asia. The common ...
, moose, mule deer, white-tailed deer, mountain goat, pronghorn, and bighorn sheep. The
Yellowstone Park bison herd The Yellowstone Park bison herd is a bison herd in Yellowstone National Park. It is probably the oldest and largest public bison herd in the United States, estimated in 2020 to be 4,800 bison. The bison in the Yellowstone Park bison herd are Am ...
is the largest public herd of American bison in the United States. Bison once numbered between 30 and 60 million individuals throughout North America, and Yellowstone remains one of their last strongholds. Their populations had increased from less than 50 in the park in 1902 to 4,000 by 2003. The Yellowstone Park bison herd reached a peak in 2005 with 4,900 animals. Despite a summer estimated population of 4,700 in 2007, the number dropped to 3,000 in 2008 after a harsh winter and controversial brucellosis management strategies which sent hundreds to slaughter. The Yellowstone Park bison herd is believed to be one of only four free roaming and genetically pure herds on public lands in North America. The other three herds are the Henry Mountains bison herd of Utah, at Wind Cave National Park in South Dakota and in Elk Island National Park in Alberta. The relatively large bison populations are a concern for ranchers, who fear that the species can transmit bovine diseases to their domesticated cousins. About half of Yellowstone's bison have been exposed to brucellosis, a bacterial disease that came to North America with European cattle that may cause cattle to miscarriage, miscarry. The disease has little effect on park bison, and no reported cases of transmission from wild bison to domestic livestock have been filed. However, the Animal and Plant Health Inspection Service (APHIS) has stated that bison are the "likely source" of the spread of the disease in cattle in Wyoming and North Dakota. Elk also carry the disease, and are believed to have transmitted the infection to horses and cattle. To combat the perceived threat of brucellosis transmission to cattle, national park personnel regularly corral bison herds back into the park when they venture outside of the area's borders. During the winter of 1996–97, the bison herd was so large that 1,079 bison that had exited the park were either shot or sent to slaughter. Animal rights activists argue that this is a cruel practice, and that the possibility for disease transmission is not as great as some ranchers maintain. Ecologists point out that the bison are merely traveling to seasonal grazing areas that lie within the Greater Yellowstone Ecosystem that have been converted to cattle grazing, some of which are within National Forests and are leased to private ranchers. APHIS has stated that with vaccinations and other means, brucellosis can be eliminated from the bison and elk herds throughout Yellowstone. Starting in 1914, in an effort to protect elk populations, the U.S. Congress appropriated funds to be used for the purposes of "destroying wolves, prairie dogs, and other animals injurious to agriculture and animal husbandry" on public lands. Park Service hunters carried out these orders, and by 1926 they had killed 136 wolves. Gradually, wolves were virtually History of wolves in Yellowstone, eliminated from Yellowstone. Further exterminations continued until the National Park Service ended the practice in 1935. With the passing of the Endangered Species Act in 1973, the wolf was one of the first mammal species listed. After the wolves were extirpated from Yellowstone, the coyote then became the park's top canine predator. Since the coyote is not able to bring down large animals, this lack of an apex predator resulted in a marked increase in lame and sick megafauna. By the 1990s, the Federal government had reversed its views on wolves. In a controversial decision by the United States Fish and Wildlife Service, U.S. Fish and Wildlife Service (which oversees threatened and endangered species), northwestern wolves imported from Canada were reintroduced into the park. Reintroduction efforts have been successful, with populations remaining relatively stable. A survey conducted in 2005 reported that there were 13 wolf packs, totaling 118 individuals in Yellowstone and 326 in the entire ecosystem. These park figures were lower than those reported in 2004, but may be attributable to wolf migration to other nearby areas as suggested by the substantial increase in the Montana population during that interval. Almost all the wolves documented were descended from the 66 wolves reintroduced in 1995–96. The recovery of populations throughout the states of Wyoming, Montana and Idaho has been so successful that on February 27, 2008, the U.S. Fish and Wildlife Service removed the Northern Rocky Mountain wolf population from the Lists of IUCN Red List endangered species, endangered species list. American black bear, Black bears are common in the park and were a park symbol due to visitor interaction with the bears starting in 1910. Feeding and close contact with bears has not been permitted since the 1960s to reduce their desire for human foods. Yellowstone is one of the few places in the United States where black bears can be seen coexisting with grizzly bears. Black bear observations occur most often in the park's northern ranges, and in the Bechler River, Bechler area which is in the park's southwestern corner. , an estimated 700 grizzly bears were living in the Greater Yellowstone Ecosystem, with about 150 grizzlies living wholly or partially within Yellowstone National Park. The grizzly was initially listed as a threatened species in the contiguous United States on July 28, 1975, by the Fish and Wildlife Service. The grizzly bear was taken off the United States Fish and Wildlife Service list of endangered mammals and birds, endangered species list in 2007."Grizzly Bears & the Endangered Species Act"
''nps.gov''. National Park Service. October 5, 2018

from the original on October 13, 2018. Retrieved December 19, 2018.
Opponents of delisting the grizzly expressed concerns that states might once again allow hunting and that better conservation measures were needed to ensure a sustainable population. A federal district judge overturned the delisting ruling in 2009, reinstating the grizzly; however, the grizzly was once again removed from the list in 2017. In September 2018, a US district judge ruled that the grizzly's protections must be restored in full, arguing the Fish and Wildlife Service was mistaken in removing the bear from the threatened status list. Regardless of the rulings, hunting is prohibited within Yellowstone National Park. Hunters who legally hunt animals outside park boundaries may transport the carcass through the park with a permit. Population figures for elk are in excess of 30,000—the largest population of any large mammal species in Yellowstone. The northern herd has decreased enormously since the mid‑1990s; this has been attributed to wolf predation and causal effects such as elk using more forested regions to evade predation, consequently making it harder for researchers to accurately count them. The northern herd migrates west into southwestern Montana in the winter. The southern herd migrates southward, and the majority of these elk winter on the National Elk Refuge, immediately southeast of Grand Teton National Park. The southern herd migration is the largest mammalian migration remaining in the U.S. outside of Alaska. In 2003 the tracks of one female lynx and her cub were spotted and followed for over . Fecal material and other evidence obtained were tested and confirmed to be those of a lynx. No visual confirmation was made, however. Lynx have not been seen in Yellowstone since 1998, though DNA taken from hair samples obtained in 2001 confirmed that lynx were at least transient to the park. Other less commonly seen mammals include the mountain lion and wolverine. The mountain lion has an estimated population of only 25 individuals parkwide. Accurate population figures for the wolverine are not known. These uncommon and rare mammals provide insight into the health of protected lands such as Yellowstone and help managers make determinations as to how best to preserve habitats. Eighteen species of fish live in Yellowstone, including the core range of the Yellowstone cutthroat trout—a fish highly sought by fishing, anglers. The Yellowstone cutthroat trout has faced several threats since the 1980s, including the suspected illegal introduction into Yellowstone Lake of lake trout, an invasive species which consume the smaller cutthroat trout. Although lake trout were established in Shoshone Lake, Shoshone and Lewis Lake (Wyoming), Lewis lakes (on the Snake River drainage) after U.S. Government stocking operations in 1890, it was never officially introduced into the Yellowstone River drainage. The cutthroat trout has also faced an ongoing drought, as well as the accidental introduction of a parasite—Myxobolus cerebralis, whirling disease—which causes a terminal nervous system disease in younger fish. Since 2001, all native sport fish species caught in Yellowstone waterways are subject to a catch and release regulations. Yellowstone is also home to seven species of reptiles, including the painted turtle, rubber Rubber boa, boa, and Crotalus viridis, prairie rattlesnake, bullsnake, sagebrush lizard, Garter snake, valley garter snake and wandering garter snake and four species of amphibians, including the boreal chorus frog, tiger salamander, western toad and columbia spotted frog. Three hundred eleven species of birds have been reported, almost half of which nest in Yellowstone. In 1999, twenty-six pairs of nesting bald eagle were documented. Extremely rare sightings of whooping cranes have been recorded, however only three examples of this species are known to live in the Rocky Mountains, out of 385 known worldwide. Other birds, considered to be species of special concern because of their rarity in Yellowstone, include the common loon, harlequin duck, osprey, peregrine falcon and the trumpeter swan.


Forest fires

As
wildfire A wildfire, forest fire, bushfire, wildland fire or rural fire is an unplanned, uncontrolled and unpredictable fire in an area of Combustibility and flammability, combustible vegetation. Depending on the type of vegetation present, a wildfire ...
is a natural part of most ecosystems, plants that are Indigenous (ecology), indigenous to Yellowstone have adapted in a variety of ways. Rocky Mountain Douglas-fir, Douglas-fir have a thick bark which protects the inner section of the tree from most fires.
Lodgepole Pine ''Pinus contorta'', with the common names lodgepole pine and shore pine, and also known as twisted pine, and contorta pine, is a common tree in western North America. It is common near the ocean shore and in dry montane forests to the subalpin ...
s—the most common tree species in the park—generally have cones that are only opened by the heat of fire. Their seeds are held in place by a tough resin, and fire assists in melting the resin, allowing the seeds to disperse. Fire clears out dead and downed wood, providing fewer obstacles for lodgepole pines to flourish.
Subalpine Fir ''Abies lasiocarpa'', the subalpine fir or Rocky Mountain fir, is a western North American fir tree. Description ''Abies lasiocarpa'' is a medium-sized evergreen conifer with a very narrow conic crown, growing to tall, exceptionally , with a t ...
,
Engelmann Spruce ''Picea engelmannii'', with the common names Engelmann spruce, white spruce, mountain spruce, and silver spruce, is a species of spruce native to western North America. It is mostly a high-altitude mountain tree but also appears in watered canyon ...
,
Whitebark Pine ''Pinus albicaulis'', known by the common names whitebark pine, white bark pine, white pine, pitch pine, scrub pine, and creeping pine, is a conifer tree native to the mountains of the western United States and Canada, specifically subalpine ...
, and other species tend to grow in colder and moister areas, where fire is less likely to occur. Populus tremuloides, Aspen trees sprout new growth from their roots, and even if a severe fire kills the tree above ground, the roots often survive unharmed because they are insulated from the heat by soil. The National Park Service estimates that in natural conditions, grasslands in Yellowstone burned an average of every 20 to 25 years, while forests in the park would experience fire about every 300 years. About thirty-five natural forest fires are ignited each year by lightning, while another six to ten are started by people—in most cases by accident. Yellowstone National Park has three fire lookout, fire lookout towers, each staffed by trained fire fighters. The easiest one to reach is atop Mount Washburn, which has interpretive exhibits and an observation deck open to the public. The park also monitors fire from the air and relies on visitor reports of smoke and/or flames. Fire towers are staffed almost continuously from late June to mid-September—the primary fire season. Fires burn with the greatest intensity in the late afternoon and evening. Few fires burn more than , and the vast majority of fires reach only a little over an acre (0.5 ha) before they burn themselves out. Fire management focuses on monitoring dead and down wood quantities, soil and tree moisture, and the weather, to determine those areas most vulnerable to fire should one ignite. Current policy is to suppress all human caused fires and to evaluate natural fires, examining the benefit or detriment they may pose on the ecosystem. If a fire is considered to be an immediate threat to people and structures, or will burn out of control, then fire suppression is performed. In an effort to minimize the chances of out of control fires and threats to people and structures, park employees do more than just monitor the potential for fire. Controlled burns are prescribed fires which are deliberately started to remove dead timber under conditions which allow fire fighters an opportunity to carefully control where and how much wood is consumed. Natural fires are sometimes considered prescribed fires if they are left to burn. In Yellowstone, unlike some other parks, there have been very few fires deliberately started by employees as prescribed burns. However, over the last 30 years, over 300 natural fires have been allowed to burn naturally. In addition, fire fighters remove dead and down wood and other hazards from areas where they will be a potential fire threat to lives and property, reducing the chances of fire danger in these areas. Fire monitors also regulate fire through educational services to the public and have been known to temporarily ban campfires from campgrounds during periods of high fire danger. The common notion in early United States land management policies was that all forest fires were bad. Fire was seen as a purely destructive force and there was little understanding that it was an integral part of the ecosystem. Consequently, until the 1970s, when a better understanding of wildfire was developed, all fires were suppressed. This led to an increase in dead and dying forests, which would later provide the fuel load for fires that would be much harder, and in some cases, impossible to control. Fire Management Plans were implemented, detailing that natural fires should be allowed to burn if they posed no immediate threat to lives and property. The spring season of 1988 was wet, but by summer, drought began moving in throughout the northern Rockies, creating the driest year on record to that point. Grasses and plants which grew well in the early summer from the abundant spring moisture produced plenty of grass, which soon turned to dry tinder. The National Park Service began firefighting efforts to keep the fires under control, but the extreme drought made suppression difficult. Between July 15 and 21, 1988, fires quickly spread from throughout the entire Yellowstone region, which included areas outside the park, to on the park land alone. By the end of the month, the fires were out of control. Large fires burned together, and on August 20, 1988, the single worst day of the fires, more than were consumed. Seven large fires were responsible for 95% of the that were burned over the next couple of months. The cost of 25,000 firefighters and U.S. military forces participating in the suppression efforts was 120 million dollars. By the time winter brought snow that helped extinguish the last flames, the fires had destroyed 67 structures and caused several million dollars in damage. Though no civilians died, two personnel associated with the firefighting efforts were killed. Contrary to media reports and speculation at the time, the fires killed very few park animals—surveys indicated that only about 345 elk (of an estimated 40,000–50,000), 36 deer, 12 moose, 6 black bears, and 9 bison had perished. Changes in fire management policies were implemented by land management agencies throughout the United States, based on knowledge gained from the 1988 fires and the evaluation of scientists and experts from various fields. By 1992, Yellowstone had adopted a new fire management plan which observed stricter guidelines for the management of natural fires.


Climate and weather

Yellowstone climate is greatly influenced by altitude, with lower elevations generally found to be warmer year-round. The record high temperature was in 2002, while the coldest temperature recorded is in 1933. During the summer months of June to early September, daytime highs are normally in the range, while night time lows can go to below freezing (0 °C) especially at higher altitudes. Summer afternoons are frequently accompanied by thunderstorms. Spring and fall temperatures range between with nights in the teens to single digits (−5 to −20 °C). Winter in Yellowstone is accompanied by high temperatures usually between zero and 20 °F (−20 to −5 °C) and nighttime temperatures below 0  °F (−18 °C) for most of the winter. Precipitation in Yellowstone is highly variable and ranges from annually near Mammoth Hot Springs, to in the southwestern sections of the park. The precipitation of Yellowstone is greatly influenced by the moisture channel formed by the Snake River Plain to the west that was, in turn, formed by Yellowstone itself. Snow is possible in any month of the year, but most common between November and April, with averages of annually around Yellowstone Lake, to twice that amount at higher elevations. The climate at Yellowstone Lake is classified as Subarctic climate, subarctic (Dfc), according to Köppen-Geiger climate classification system, Köppen-Geiger climate classification, while at the park headquarters the classification is Humid continental climate, humid continental (Dfb). Tornadoes in Yellowstone are rare; however, on July 21, 1987, the most powerful tornado recorded in Wyoming touched down in the Teton Wilderness of Bridger-Teton National Forest and hit Yellowstone National Park. Called the Teton–Yellowstone tornado, it was classified as an Fujita Scale, F4, with wind speeds estimated at between . The tornado left a path of destruction wide, and long, and leveled of mature pine forest. In June 2022, the Park closed entrances and evacuated visitors after experiencing record-level rainfall and 2022 Montana floods, flooding that caused multiple road and bridge failures, power outages, and mudslides. A combination of heavy rain and rapid snow melt resulted in the Yellowstone River rising to a new record height at , breaking a previous record of set in 1918. Flooding on the Lamar River reached , beating a 1996 record of . Damage from the flooding includes washed out roads and bridges, and damage to infrastructure systems including electricity, water and wastewater systems. It's unlikely that the park will be able to reopen the north entrance by Gardiner, MT, or the northeast entrance near Cooke City, MT, during the 2022 season. The park partially reopened Wednesday, June 22, after a 9-day closure. To limit the nearly one million visitors per month that visit in the summer, the park has restricted entry to cars based on license plates. Cars with license plates ending in even numbers can enter on even numbered dates, and plates ending in odd numbers can enter on odd numbered dates.


Recreation

Yellowstone ranks among the most popular national parks in the United States. Since the mid-1960s, at least 2 million tourists have visited the park almost every year. Average annual visitation increased to 3.5 million during the ten-year period from 2007 to 2016, with a record of 4,257,177 recreational visitors in 2016. July is the busiest month for Yellowstone National Park. At peak summer levels, 3,700 employees work for Yellowstone National Park concessionaires. Concessionaires manage nine hotels and lodges, with a total of 2,238 hotel rooms and cabins available. They also oversee gas stations, stores and most of the campgrounds. Another 800 employees work either permanently or seasonally for the National Park Service. Park service roads lead to major features; however, road reconstruction has produced temporary road closures. Yellowstone is in the midst of a long term road reconstruction effort, which is hampered by a short repair season. In the winter, all roads aside from the one which enters from
Gardiner, Montana Gardiner is a unincorporated community in Park County, Montana, United States, along the 45th parallel. As of the 2020 census, the population of the community and nearby areas was 833. Gardiner was officially founded in 1880. The area has s ...
, and extends to Cooke City, Montana, are closed to wheeled vehicles. Park roads are closed to wheeled vehicles from early November to mid April, but some park roads remain closed until mid-May. The park has of paved roads which can be accessed from five different entrances. There is no public transportation available inside the park, but several tour companies can be contacted for guided (including Self-guided tour, self-guided) motorized transport. In the winter, concessionaires operate guided
snowmobile A snowmobile, also known as a Ski-Doo, snowmachine, sled, motor sled, motor sledge, skimobile, or snow scooter, is a motorized vehicle designed for winter travel and recreation on snow. It is designed to be operated on snow and ice and does not ...
and
snow coach A snow coach is a specialized passenger transport vehicle designed to operate over snow or ice, similar to a large, multi-passenger snowcat that is equipped with bus-style seating. These vehicles may have multiple sets of very large, low-pressur ...
tours, though their numbers and access are based on quotas established by the National Park Service. Facilities in the Old Faithful, Canyon and Mammoth Hot Springs areas of the park are very busy during the summer months. Traffic jams created by road construction or by people observing wildlife can result in long delays. The National Park Service maintains nine visitor centers and museums and is responsible for maintenance of historical structures and many of the other 2,000 buildings. These structures include National Historical Landmarks such as the Old Faithful Inn built from 1903 to 1904 and the entire Fort Yellowstone, Fort Yellowstone – Mammoth Hot Springs Historic District. An historical and educational tour is available at Fort Yellowstone which details the history of the National Park Service and the development of the park. Campfire programs, guided walks and other interpretive presentations normally available at numerous locations in the summer, and on a limited basis during other seasons were suspended in 2021 as a COVID-19 response. Camping is available at a dozen campgrounds with more than 2,000 campsites. Camping is also available in surrounding National Forests, as well as in Grand Teton National Park to the south. Backcountry campsites are accessible only by foot or by horseback riding, horseback and require a permit. There are of hiking trails available. The park is not considered to be a good destination for mountaineering because of the instability of volcanic rock which predominates. Visitors with pets are required to keep them on a leash at all times and are limited to areas near roadways and in "frontcountry" zones such as drive in campgrounds. Around thermal features, wooden and paved trails have been constructed to ensure visitor safety, and most of these areas are handicapped accessible. The National Park Service maintains a year-round clinic at Mammoth Hot Springs and provides emergency services throughout the year. Hunting is not permitted, though it is allowed in the surrounding national forests during open season. Fishing is a popular activity, and a Yellowstone Park fishing license is required to fish in park waters. Many park waters are fly fishing only and all native fish species are catch and release only. Boating is prohibited on rivers and creeks except for a stretch of the Lewis River between Lewis Lake (Wyoming), Lewis and Shoshone Lake, Shoshone lakes, and it is open to non-motorized use only. Yellowstone Lake has a marina at Bridge Bay while there is a boat ramp at the Lewis lake campground. In the early history of the park, visitors were allowed, and sometimes even encouraged, to feed the bears. Visitors welcomed the chance to get their pictures taken with the bears, who had learned to beg for food. This led to numerous injuries to humans each year. In 1970, park officials changed their policy and started a vigorous program to educate the public on the dangers of close contact with bears, and to try to eliminate opportunities for bears to find food in campgrounds and trash collection areas. Although it has become more difficult to observe bears in recent years, the number of human injuries and deaths has taken a significant drop and visitors are in less danger. The eighth recorded bear-related death in the park's history occurred in August 2015. Other protected lands in the region include Caribou-Targhee National Forest, Caribou-Targhee, Gallatin National Forest, Gallatin, Custer National Forest, Custer, Shoshone National Forest, Shoshone and Bridger-Teton National Forests. The National Park Service's John D. Rockefeller, Jr. Memorial Parkway is to the south and leads to Grand Teton National Park. The famed Beartooth Highway provides access from the northeast and has spectacular high altitude scenery. Nearby communities include West Yellowstone, Montana; Cody, Wyoming; Red Lodge, Montana; Ashton, Idaho; and
Gardiner, Montana Gardiner is a unincorporated community in Park County, Montana, United States, along the 45th parallel. As of the 2020 census, the population of the community and nearby areas was 833. Gardiner was officially founded in 1880. The area has s ...
. The closest air transport is available by way of Bozeman, Montana; Billings, Montana; Jackson, Wyoming, Jackson; Cody, Wyoming, or Idaho Falls, Idaho. Salt Lake City, to the south, is the closest large metropolitan area.


Legal jurisdiction

The entire park is within the jurisdiction of the United States District Court for the District of Wyoming, making it the only federal court district that includes portions of more than one state (Idaho, Montana, and Wyoming). Law professor Brian C. Kalt has argued that it may be impossible to impanel a jury in compliance with the Vicinage Clause of the Sixth Amendment to the United States Constitution, Sixth Amendment for a crime committed solely in the unpopulated Idaho portion of the park (and that it would be difficult to do so for a crime committed solely in the lightly populated Montana portion). One defendant, who was accused of a wildlife-related crime in the Montana portion of the park, attempted to raise this argument but eventually pleaded guilty, with the plea deal including his specific agreement not to raise the issue in his appeal.Brian C. Kalt, Tabloid Constitutionalism, 96 1971 (2008).


See also

* Bibliography of Yellowstone National Park * List of national parks of the United States * Making North America, ''Making North America'' (2015 PBS film) * National Parks in Idaho * Outline of Yellowstone National Park


References


Further reading

* Whittlesey, Lee H. (2002), "Native Americans, the Earliest Interpreters: What is Known About Their Legends and Stories of Yellowstone National Park and the Complexities of Interpreting Them", ''The George Wright Forum'', published by the George Wright Society, Vol. 19, No. 3, pp. 40–51. .


External links

* of th
National Park Service

Travertine: Yellowstone’s Hydrothermal Timekeeper
USGS May 24, 2021

from th
Library of Congress



The Yellowstone magmatic system from the mantle plume to the upper crust
a
Science
(registration required)
BYU Larsen Yellowstone collection
at the L. Tom Perry Special Collections Library of Brigham Young University
Yellowstone articles, photos and videos
a
National Geographic

Photographic library of the U.S. Geological Surveyarchive
* * * *Historic American Engineering Record (HAER) documentation: ** ** ** {{Authority control Yellowstone National Park, 1872 establishments in Idaho Territory 1872 establishments in Montana Territory 1872 establishments in Wyoming Territory 1872 establishments in the United States Biosphere reserves of the United States Civilian Conservation Corps in Idaho Civilian Conservation Corps in Montana Civilian Conservation Corps in Wyoming Geysers of Wyoming Greater Yellowstone Ecosystem Historic American Engineering Record in Montana History of the Rocky Mountains History of Wyoming Hot springs of Wyoming Hot springs of Teton County, Wyoming Landforms of Park County, Wyoming Landforms of Teton County, Wyoming National parks in Idaho National parks in Montana National parks in Wyoming National parks of the Rocky Mountains Protected areas established in 1872 Protected areas of Fremont County, Idaho Protected areas of Gallatin County, Montana Protected areas of Park County, Montana Protected areas of Park County, Wyoming Protected areas of Teton County, Wyoming Regions of Wyoming World Heritage Sites in the United States Yellowstone Caldera