Interstate 15
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Interstate 15 (I-15) is a major
Interstate Highway The Dwight D. Eisenhower National System of Interstate and Defense Highways, commonly known as the Interstate Highway System, is a network of controlled-access highways that forms part of the National Highway System in the United States. Th ...
in the western
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...
, running through
Southern California Southern California (commonly shortened to SoCal) is a geographic and Cultural area, cultural region that generally comprises the southern portion of the U.S. state of California. It includes the Los Angeles metropolitan area, the second most po ...
and the
Intermountain West The Intermountain West, or Intermountain Region, is a geographic and geological region of the Western United States. It is located between the front ranges of the Rocky Mountains on the east and the Cascade Range and Sierra Nevada on the wes ...
. I-15 begins near the
Mexican border Mexico shares international borders with three nations: *To the north the United States–Mexico border, which extends for a length of through the states of Baja California, Sonora, Chihuahua, Coahuila, Nuevo León and Tamaulipas. *To the southe ...
in
San Diego County San Diego County (), officially the County of San Diego, is a county in the southwestern corner of the U.S. state of California. As of the 2020 census, the population was 3,298,634, making it California's second-most populous county and the f ...
and stretches north to
Alberta, Canada Alberta ( ) is one of the thirteen provinces and territories of Canada. It is part of Western Canada and is one of the three prairie provinces. Alberta is bordered by British Columbia to the west, Saskatchewan to the east, the Northwest Territ ...
, passing through the states of
California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...
,
Nevada Nevada ( ; ) is a U.S. state, state in the Western United States, Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. N ...
,
Arizona Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...
,
Utah Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to it ...
,
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 Wyom ...
, and
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 ...
. The Interstate serves the cities of
San Diego San Diego ( , ; ) is a city on the Pacific Ocean coast of Southern California located immediately adjacent to the Mexico–United States border. With a 2020 population of 1,386,932, it is the List of United States cities by population, eigh ...
,
San Bernardino San Bernardino (; Spanish language, Spanish for Bernardino of Siena, "Saint Bernardino") is a city and county seat of San Bernardino County, California, United States. Located in the Inland Empire region of Southern California, the city had a ...
,
Las Vegas Las Vegas (; Spanish for "The Meadows"), often known simply as Vegas, is the 25th-most populous city in the United States, the most populous city in the state of Nevada, and the county seat of Clark County. The city anchors the Las Vegas ...
, St. George, Provo,
Salt Lake City Salt Lake City (often shortened to Salt Lake and abbreviated as SLC) is the Capital (political), capital and List of cities and towns in Utah, most populous city of Utah, United States. It is the county seat, seat of Salt Lake County, Utah, Sal ...
, Ogden,
Pocatello Pocatello () is the county seat of and largest city in Bannock County, with a small portion on the Fort Hall Indian Reservation in neighboring Power County, in the southeastern part of the U.S. state of Idaho. It is the principal city of the P ...
,
Idaho Falls Idaho Falls ( Shoshoni: Dembimbosaage) is a city in and the county seat of Bonneville County, Idaho, United States. It is the state's largest city outside the Boise metropolitan area. As of the 2020 census, the population of Idaho Falls was 6 ...
,
Butte __NOTOC__ In geomorphology, a butte () is an isolated hill with steep, often vertical sides and a small, relatively flat top; buttes are smaller landforms than mesas, plateaus, and tablelands. The word ''butte'' comes from a French word mea ...
, Helena, and
Great Falls Great may refer to: Descriptions or measurements * Great, a relative measurement in physical space, see Size * Greatness, being divine, majestic, superior, majestic, or transcendent People * List of people known as "the Great" *Artel Great (born ...
. It also passes close to the urban areas of
Los Angeles Los Angeles ( ; es, Los Ángeles, link=no , ), often referred to by its initials L.A., is the largest city in the state of California and the second most populous city in the United States after New York City, as well as one of the world' ...
,
Orange Orange most often refers to: *Orange (fruit), the fruit of the tree species '' Citrus'' × ''sinensis'' ** Orange blossom, its fragrant flower *Orange (colour), from the color of an orange, occurs between red and yellow in the visible spectrum * ...
, and
Riverside Riverside may refer to: Places Australia * Riverside, Tasmania, a suburb of Launceston, Tasmania Canada * Riverside (electoral district), in the Yukon * Riverside, Calgary, a neighbourhood in Alberta * Riverside, Manitoba, a former rural m ...
counties, California. The stretches of I-15 in Idaho, Utah, and Arizona have been designated as the "Veterans Memorial Highway". The southern end is at a junction with I-8 and State Route 15 (SR 15) in
San Diego San Diego ( , ; ) is a city on the Pacific Ocean coast of Southern California located immediately adjacent to the Mexico–United States border. With a 2020 population of 1,386,932, it is the List of United States cities by population, eigh ...
, and the northern end is at a connection with
Alberta Highway 4 Alberta Provincial Highway No. 4, commonly referred to as Highway 4, is a highway in southern Alberta, Canada that connects Highway 3 in Lethbridge to Interstate 15 in Montana. The highway was designated in 1999 as the First ...
at the Sweetgrass–Coutts Border Crossing. I-15 was built to connect the Inland Empire with San Diego in California, facilitate tourism access to Las Vegas, provide access to the
Arizona Strip The Arizona Strip is the part of Arizona lying north of the Colorado River. Despite being larger in area than several U.S. states, the entire region has a population of fewer than 10,000 people. Consisting of northeastern Mohave County and n ...
, interconnect all of the
metropolitan statistical area In the United States, a metropolitan statistical area (MSA) is a geographical region with a relatively high population density at its core and close economic ties throughout the area. Such regions are neither legally Incorporated town, incorporate ...
s in Utah except for Logan, and provide freeway bypasses for
Pocatello Pocatello () is the county seat of and largest city in Bannock County, with a small portion on the Fort Hall Indian Reservation in neighboring Power County, in the southeastern part of the U.S. state of Idaho. It is the principal city of the P ...
,
Idaho Falls Idaho Falls ( Shoshoni: Dembimbosaage) is a city in and the county seat of Bonneville County, Idaho, United States. It is the state's largest city outside the Boise metropolitan area. As of the 2020 census, the population of Idaho Falls was 6 ...
, and
Great Falls Great may refer to: Descriptions or measurements * Great, a relative measurement in physical space, see Size * Greatness, being divine, majestic, superior, majestic, or transcendent People * List of people known as "the Great" *Artel Great (born ...
. Since its creation, I-15 has served as a long-haul route for
North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...
n commerce. It is now officially chartered for this purpose: from the junction of I-515 in
Las Vegas Las Vegas (; Spanish for "The Meadows"), often known simply as Vegas, is the 25th-most populous city in the United States, the most populous city in the state of Nevada, and the county seat of Clark County. The city anchors the Las Vegas ...
to the
Canadian border Canadians (french: Canadiens) are people identified with the country of Canada. This connection may be residential, legal, historical or cultural. For most Canadians, many (or all) of these connections exist and are collectively the source of ...
, I-15 forms part of the
CANAMEX Corridor The CANAMEX corridor is a series of improvements to freeways and other transportation infrastructure linking Canada to Mexico through the United States. The corridor was established under the North American Free Trade Agreement. Currently the corr ...
, a
High Priority Corridor The Intermodal Surface Transportation Efficiency Act of 1991 (ISTEA, pronounced ''Ice-Tea'') is a United States federal law that posed a major change to transportation planning and policy, as the first U.S. federal legislation on the subject in ...
, as a result of the
North American Free Trade Agreement The North American Free Trade Agreement (NAFTA ; es, Tratado de Libre Comercio de América del Norte, TLCAN; french: Accord de libre-échange nord-américain, ALÉNA) was an agreement signed by Canada, Mexico, and the United States that crea ...
. Since the construction of I-15, California, Idaho, Nevada, and Utah have consistently ranked in the fastest-growing areas of the United States. As a result, the route of I-15 has substantially increased in population and commuter traffic.


Route description

, - , CA , , - , NV , , - , AZ , , - , UT , , - , ID , , - , MT , , - , Total , This highway's southern terminus is in
San Diego, California San Diego ( , ; ) is a city on the Pacific Ocean coast of Southern California located immediately adjacent to the Mexico–United States border. With a 2020 population of 1,386,932, it is the eighth most populous city in the United States ...
, at I-8, although via SR 15, a southern extension of the freeway, the route connects to
I-5 Interstate 5 (I-5) is the main north–south Interstate Highway on the West Coast of the United States, running largely parallel to the Pacific coast of the contiguous U.S. from Mexico to Canada. It travels through the states of Californi ...
just north of the Mexico–US border. The northern terminus is in Sweet Grass, Montana, at the Canada–US border, where it becomes
Alberta Highway 4 Alberta Provincial Highway No. 4, commonly referred to as Highway 4, is a highway in southern Alberta, Canada that connects Highway 3 in Lethbridge to Interstate 15 in Montana. The highway was designated in 1999 as the First ...
. It is long from San Diego to Sweet Grass.


California

North of its junction with SR 91 in
Corona Corona (from the Latin for 'crown') most commonly refers to: * Stellar corona, the outer atmosphere of the Sun or another star * Corona (beer), a Mexican beer * Corona, informal term for the coronavirus SARS-CoV-2, which causes the COVID-19 di ...
, the route roughly follows the former routes of State Route 31. North of
Devore Devore may refer to: * Devoré, a fabric technique *Devore, San Bernardino, California *Devore, Indiana People with the surname *Chuck DeVore (born 1962), American politician * Daniel Bradford Devore, (1860–1956), American brigadier general *Doro ...
, the highway follows the approximate alignment of historic US Route 66 along with US 91 and US 395. US 395 breaks away at Hesperia and the route continues on a direct path to Barstow to the north. Meanwhile, the old alignments of US 91 and US 66 follow the
Mojave River The Mojave River is an intermittent river in the eastern San Bernardino Mountains and the Mojave Desert in San Bernardino County, California, United States. Most of its flow is underground, while its surface channels remain dry most of the time, ...
from
Victorville Victorville is a city in Victor Valley in San Bernardino County, California. Its population as of the 2020 census was 134,810. History In 1858, Aaron G. Lane came to what is now known as Victorville and founded a waystation called "Lane's Cro ...
to Barstow along the National Trails Highway. At that point, I-15 follows the old route of US 91 exclusively as US 66 turned east toward Needles. For many parts of the highway, high-voltage powerlines, such as
Path 46 Path 46, also called West of Colorado River, Arizona-California West-of-the-River Path (WOR), is a set of fourteen high voltage (500 kV & 230 kV) alternating-current transmission lines that are located in southeast California and Nevada up to the ...
and
Path 27 Path 27, also called the Intermountain or the Southern Transmission System (STS), is a high-voltage direct current (HVDC) electrical transmission line running from the coal-fired Intermountain Power Plant near Delta, Utah to the Adelanto Conver ...
, almost all originating from the Hoover Dam, follow the freeway. Many of these link distant power stations to the
Los Angeles Los Angeles ( ; es, Los Ángeles, link=no , ), often referred to by its initials L.A., is the largest city in the state of California and the second most populous city in the United States after New York City, as well as one of the world' ...
metropolitan area. The southern starting point of I-15 was in 1957 planned to be in
San Bernardino San Bernardino (; Spanish language, Spanish for Bernardino of Siena, "Saint Bernardino") is a city and county seat of San Bernardino County, California, United States. Located in the Inland Empire region of Southern California, the city had a ...
, at the interchange with the San Bernardino Freeway (then US 70/US 99, now
I-10 Interstate 10 (I-10) is the southernmost cross-country highway in the American Interstate Highway System. I-10 is the fourth-longest Interstate in the United States at , following I-90, I-80, and I-40. This freeway is part of the originally pl ...
). This was logical as I-15 was following the old alignment of the historic Route 66 which passed through San Bernardino. The segment was completed accordingly. In 1964, legislation was later passed to extend the Interstate to
San Diego San Diego ( , ; ) is a city on the Pacific Ocean coast of Southern California located immediately adjacent to the Mexico–United States border. With a 2020 population of 1,386,932, it is the List of United States cities by population, eigh ...
. Instead of extending the existing freeway from the I-10 interchange south, however, the
California Department of Transportation The California Department of Transportation (Caltrans) is an executive department of the U.S. state of California. The department is part of the cabinet-level California State Transportation Agency (CalSTA). Caltrans is headquartered in Sacrame ...
drew a new segment in Devore that "branched" off of the original alignment and bypassed San Bernardino altogether. This segment's alignment is generally northeast to southwest for about . Then, in
Rancho Cucamonga Rancho Cucamonga was a Mexican land grant in present-day San Bernardino County, California, given in 1839 to the dedicated soldier, smuggler and politician Tiburcio Tapia by Mexican governor Juan Bautista Alvarado. The grant formed parts of pr ...
, its directional alignment shifts to north–south where it eventually meets with I-10 (about west of the original interchange in San Bernardino). The segment that had been built from Devore to San Bernardino was retained as an Interstate, but was renumbered as
I-215 Interstate 215 is the designation for several Interstate Highways in the United States, all of which are related to Interstate 15 (I-15): * Interstate 215 (California), a regional Interstate bypass for I-15 and a connection to I-10 that serves the ...
. Note that during the construction of I-15's present alignment, and for some time afterward, I-215 was numbered as I-15E, and its actual mileage would begin at I-10. I-15 runs for a total of in California.


Nevada

I-15 begins in Primm and continues through
Las Vegas Las Vegas (; Spanish for "The Meadows"), often known simply as Vegas, is the 25th-most populous city in the United States, the most populous city in the state of Nevada, and the county seat of Clark County. The city anchors the Las Vegas ...
along the
Las Vegas Strip The Las Vegas Strip is a stretch of Las Vegas Boulevard, Las Vegas Boulevard South in Clark County, Nevada, that is known for its concentration of resort hotels and casinos. The Strip, as it is known, is about long, and is immediately south of ...
corridor. Then, the Interstate crosses the border with
Arizona Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...
in
Mesquite Mesquite is a common name for several plants in the genus '' Prosopis'', which contains over 40 species of small leguminous trees. They are native to dry areas in the Americas. They have extremely long roots to seek water from very far under gr ...
. The Interstate in
Nevada Nevada ( ; ) is a U.S. state, state in the Western United States, Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. N ...
runs entirely in Clark County, for a distance of .


Arizona

I-15 passes through the northwestern corner of
Arizona Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...
with a total length of . The stretch is separated from the rest of the state and has one major exit, at
Beaver Dam A beaver dam or beaver impoundment is a dam built by beavers to create a pond which protects against predators such as coyotes, wolves and bears, and holds their food during winter. These structures modify the natural environment in such a way t ...
/
Littlefield, Arizona Littlefield is an unincorporated community and census-designated place in Mohave County, Arizona, United States, that is located in the Arizona Strip region. As of the 2020 census, its population was 256, down from 308 in 2010. It lies just sou ...
. It includes a spectacular section where the road twists between the narrow walls of the
Virgin River Gorge The Virgin River Gorge, located between St. George, Utah, and Beaver Dam, Arizona, is a long canyon that has been carved out by the Virgin River in northwest Arizona. The Virgin River rises on the Colorado Plateau and created the topography of ...
.


Utah

I-15 continues through
Utah Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to it ...
for . It is the main north–south connection for the state. The highway approximately follows the old alignment of US 91 from St. George to Brigham City. The highway passes through the fast-growing
Utah's Dixie Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to its ...
region in the southwestern part of the state, which includes St. George,
Cedar City Cedar City is the largest city in Iron County, Utah, United States. It is located south of Salt Lake City, and north of Las Vegas on Interstate 15. It is the home of Southern Utah University, the Utah Shakespeare Festival, the Utah Summer Gam ...
, and eventually most of the major cities and suburbs along the
Wasatch Front The Wasatch Front is a metropolitan region in the north-central part of the U.S. state of Utah. It consists of a chain of contiguous cities and towns stretched along the Wasatch Range from approximately Provo in the south to Logan in the nort ...
, including Provo,
Orem Orem is a city in Utah County, Utah, United States, in the northern part of the state. It is adjacent to Provo, Lindon, and Vineyard and is approximately south of Salt Lake City. Orem is one of the principal cities of the Provo-Orem, Utah M ...
, Sandy,
Salt Lake City Salt Lake City (often shortened to Salt Lake and abbreviated as SLC) is the Capital (political), capital and List of cities and towns in Utah, most populous city of Utah, United States. It is the county seat, seat of Salt Lake County, Utah, Sal ...
,
Layton Layton or The Laytons may refer to: Places United States * Layton, Florida, a city * Layton, Indiana, an unincorporated community * Layton Township, Pottawattamie County, Iowa * Layton, New Jersey, an unincorporated community * Layton, Pennsyl ...
, and Ogden. Near
Cove Fort Cove Fort is a fort, unincorporated community, and historical site located in Millard County, Utah. It was founded in 1867 by Ira Hinckley (the paternal grandfather of Gordon B. Hinckley) at the request of Brigham Young. One of its distinctiv ...
,
I-70 Interstate 70 (I-70) is a major east–west Interstate Highway in the United States that runs from I-15 near Cove Fort, Utah, to a park and ride lot just east of I-695 in Baltimore, Maryland, and is the fifth-longest Interstate in the c ...
begins its journey eastward across the country. The Interstate merges with
I-80 Interstate 80 (I-80) is an east–west transcontinental freeway that crosses the United States from downtown San Francisco, California, to Teaneck, New Jersey, in the New York metropolitan area. The highway was designated in 1956 as one o ...
for about from
South Salt Lake South Salt Lake is a city in Salt Lake County, Utah, United States and is part of the Salt Lake City Metropolitan Statistical Area. The population was 23,617 at the 2010 census. History Jesse Fox Jr. developed the area South Salt Lake referre ...
to just west of Downtown Salt Lake City and also merges with
I-84 Interstate 84 may refer to: * Interstate 84 (Oregon–Utah), passing through Idaho, formerly known as Interstate 80N * Interstate 84 (Pennsylvania–Massachusetts) Interstate 84 (I-84) is an Interstate Highway in the Northeaster ...
from Ogden to Tremonton. Along nearly its entire length through the state, I-15 winds its way along the western edge of a nearly continuous range of mountains (the
Wasatch Range The Wasatch Range ( ) or Wasatch Mountains is a mountain range in the western United States that runs about from the Utah-Idaho border south to central Utah. It is the western edge of the greater Rocky Mountains, and the eastern edge of the G ...
in the northern half of the state). The only exceptions are north of
Cove Fort Cove Fort is a fort, unincorporated community, and historical site located in Millard County, Utah. It was founded in 1867 by Ira Hinckley (the paternal grandfather of Gordon B. Hinckley) at the request of Brigham Young. One of its distinctiv ...
and when it passes between
Cedar City Cedar City is the largest city in Iron County, Utah, United States. It is located south of Salt Lake City, and north of Las Vegas on Interstate 15. It is the home of Southern Utah University, the Utah Shakespeare Festival, the Utah Summer Gam ...
and St. George, known as the Black Ridge, a transition zone of drastic change in elevation and climate, an area where the eastern
Great Basin The Great Basin is the largest area of contiguous endorheic basin, endorheic watersheds, those with no outlets, in North America. It spans nearly all of Nevada, much of Utah, and portions of California, Idaho, Oregon, Wyoming, and Baja California ...
, Colorado Plateau, and
Mojave Desert The Mojave Desert ( ; mov, Hayikwiir Mat'aar; es, Desierto de Mojave) is a desert in the rain shadow of the Sierra Nevada mountains in the Southwestern United States. It is named for the indigenous Mojave people. It is located primarily in ...
converge.


Idaho

I-15 passes through
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 Wyom ...
for . I-15 crosses the
Utah Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to it ...
state line in Oneida County. The highway runs through
Pocatello Pocatello () is the county seat of and largest city in Bannock County, with a small portion on the Fort Hall Indian Reservation in neighboring Power County, in the southeastern part of the U.S. state of Idaho. It is the principal city of the P ...
, Blackfoot, and
Idaho Falls Idaho Falls ( Shoshoni: Dembimbosaage) is a city in and the county seat of Bonneville County, Idaho, United States. It is the state's largest city outside the Boise metropolitan area. As of the 2020 census, the population of Idaho Falls was 6 ...
, intersecting with
I-86 Interstate 86 may refer to any of three unconnected Interstate Highways in the United States: * Interstate 86 (Pennsylvania–New York) * Interstate 86 (Idaho) * Interstate 84 (Pennsylvania–Massachusetts) Interstate 84 (I-84) is an I ...
. The last county in Idaho that I-15 passes through is Clark County. Finally, the Interstate reaches the
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 ...
state line at
Monida Pass Monida Pass is a high mountain pass in the northern Rocky Mountains of the western United States, at an elevation of above sea level on Interstate 15, and  on the Union Pacific Railroad. On the Continental Divide in the Bitterroot Range, it ...
.


Montana

I-15 continues onward through of
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 ...
through the cities of
Butte __NOTOC__ In geomorphology, a butte () is an isolated hill with steep, often vertical sides and a small, relatively flat top; buttes are smaller landforms than mesas, plateaus, and tablelands. The word ''butte'' comes from a French word mea ...
, Helena, and
Great Falls Great may refer to: Descriptions or measurements * Great, a relative measurement in physical space, see Size * Greatness, being divine, majestic, superior, majestic, or transcendent People * List of people known as "the Great" *Artel Great (born ...
, intersecting with I-90,
I-115 Interstate 115 (I-115) is a auxiliary Interstate Highway which connects I-15/ I-90 to Butte in the U.S. state of Montana. The highway is concurrent with I-15 Bus./ I-90 Bus. for its entire length. The highway travels from an incomplete in ...
, and I-315. At Sweet Grass, I-15 terminates upon crossing the Canadian border into the province of
Alberta Alberta ( ) is one of the thirteen provinces and territories of Canada. It is part of Western Canada and is one of the three prairie provinces. Alberta is bordered by British Columbia to the west, Saskatchewan to the east, the Northwest Ter ...
; however, I-15 signage is present on
Alberta Highway 4 Alberta Provincial Highway No. 4, commonly referred to as Highway 4, is a highway in southern Alberta, Canada that connects Highway 3 in Lethbridge to Interstate 15 in Montana. The highway was designated in 1999 as the First ...
southbound from
Lethbridge Lethbridge ( ) is a city in the province of Alberta, Canada. With a population of 101,482 in its 2019 Alberta municipal censuses, 2019 municipal census, Lethbridge became the fourth Alberta city to surpass 100,000 people. The nearby Canadian ...
to the
Canadian border Canadians (french: Canadiens) are people identified with the country of Canada. This connection may be residential, legal, historical or cultural. For most Canadians, many (or all) of these connections exist and are collectively the source of ...
.


History

I-15 was constructed along the route of US 91. Once I-15 was relatively intact, US 91 was decommissioned, except for one part in Northern Utah / Southern Idaho where I-15 instead followed the route of former US 191. I-15 originally had two suffixed routes. In California, I-15 had an eastern branch bypassing
San Bernardino San Bernardino (; Spanish language, Spanish for Bernardino of Siena, "Saint Bernardino") is a city and county seat of San Bernardino County, California, United States. Located in the Inland Empire region of Southern California, the city had a ...
, which was designated I-15E. I-15E was renumbered and is now
I-215 Interstate 215 is the designation for several Interstate Highways in the United States, all of which are related to Interstate 15 (I-15): * Interstate 215 (California), a regional Interstate bypass for I-15 and a connection to I-10 that serves the ...
. Present day routing of I-15 in California was originally given "I-15W" as its title while it was under construction (the original asphalt portions from Temescal Canyon to Ontario Avenue were dubbed I-15W on maps until 1974), but was never officially signed as such. In Idaho, I-15 had a western branch near
Pocatello Pocatello () is the county seat of and largest city in Bannock County, with a small portion on the Fort Hall Indian Reservation in neighboring Power County, in the southeastern part of the U.S. state of Idaho. It is the principal city of the P ...
that connected I-15 and I-84 (then I-80N). This highway was designated I-15W. It is now the western I-86.


Growth along route

Since the construction of I-15, California, Nevada, and Utah have consistently ranked in the fastest-growing areas of the United States. As a result, the route of I-15 has substantially increased in population and commuter traffic has increased the traffic burden on the freeway. Current population estimates are that more than 75 percent of the population of Utah, 19 percent of the population of California, and more than 70 percent of the population of Nevada live in counties where I-15 is the primary
Interstate Highway The Dwight D. Eisenhower National System of Interstate and Defense Highways, commonly known as the Interstate Highway System, is a network of controlled-access highways that forms part of the National Highway System in the United States. Th ...
. Similarly, in California, I-15 is seeing more commuter traffic due to the growth of the
Mojave Desert The Mojave Desert ( ; mov, Hayikwiir Mat'aar; es, Desierto de Mojave) is a desert in the rain shadow of the Sierra Nevada mountains in the Southwestern United States. It is named for the indigenous Mojave people. It is located primarily in ...
communities of Hesperia,
Victorville Victorville is a city in Victor Valley in San Bernardino County, California. Its population as of the 2020 census was 134,810. History In 1858, Aaron G. Lane came to what is now known as Victorville and founded a waystation called "Lane's Cro ...
, and Barstow. In Utah, I-15 has been near-constantly upgraded in the
Wasatch Front The Wasatch Front is a metropolitan region in the north-central part of the U.S. state of Utah. It consists of a chain of contiguous cities and towns stretched along the Wasatch Range from approximately Provo in the south to Logan in the nort ...
, and future plans released by the Utah Department of Transportation (UDOT) indicate that this will continue in the north ''and'' the far south of the state as well, due to the extremely rapid growth of Washington County and surrounding areas. In like manner,
Las Vegas Las Vegas (; Spanish for "The Meadows"), often known simply as Vegas, is the 25th-most populous city in the United States, the most populous city in the state of Nevada, and the county seat of Clark County. The city anchors the Las Vegas ...
in Nevada has seen growth along I-15, and in all of the states that it currently serves, it has recently been or is currently in the process of being upgraded to increase capacity and efficiency. The portions in Arizona, Idaho and Montana have retained their rural, long-haul character. Although Arizona has also grown substantially since the construction of I-15, this
highway A highway is any public or private road or other public way on land. It is used for major roads, but also includes other public roads and public tracks. In some areas of the United States, it is used as an equivalent term to controlled-access ...
serves only the isolated corner of northwestern Arizona. Due to this rapid area growth, the I-15 corridor is the focus of several mass transit projects. The
Las Vegas Monorail The Las Vegas Monorail is a automated monorail mass transit system located adjacent to the Las Vegas Strip, in Clark County, Nevada, United States. It connects several large casinos in the unincorporated communities of Paradise and Winch ...
, ''
FrontRunner FrontRunner is a commuter rail train operated by the Utah Transit Authority that operates along the Wasatch Front in north-central Utah with service from the Ogden Intermodal Transit Center in central Weber County through Davis County, Salt ...
''
commuter rail Commuter rail, or suburban rail, is a passenger rail transport service that primarily operates within a metropolitan area, connecting commuters to a central city from adjacent suburbs or commuter towns. Generally commuter rail systems are con ...
system, and TRAX light rail in
Salt Lake City Salt Lake City (often shortened to Salt Lake and abbreviated as SLC) is the Capital (political), capital and List of cities and towns in Utah, most populous city of Utah, United States. It is the county seat, seat of Salt Lake County, Utah, Sal ...
are mass transit lines loosely parallel to I-15 that are now in operation. Between Los Angeles and Las Vegas has long been proposed as a maglev train route; in 2004 the
California–Nevada Interstate Maglev The California–Nevada Interstate Maglev project was a proposed Maglev train line from Las Vegas, Nevada, to Anaheim, California. One segment would run from Las Vegas to Primm, Nevada, with proposed service to the Las Vegas area's forthcoming ...
project held public meetings on the plan.


Future

The segment signed as SR 15 from
I-5 Interstate 5 (I-5) is the main north–south Interstate Highway on the West Coast of the United States, running largely parallel to the Pacific coast of the contiguous U.S. from Mexico to Canada. It travels through the states of Californi ...
to I-8 in
San Diego San Diego ( , ; ) is a city on the Pacific Ocean coast of Southern California located immediately adjacent to the Mexico–United States border. With a 2020 population of 1,386,932, it is the List of United States cities by population, eigh ...
is planned to be redesignated as part of I-15 once this segment is completely upgraded to Interstate standards, namely where the freeway's interchange with SR 94 is concerned. The interchange currently has left-exits and blind merges, and is due to be updated with a long-awaited widening of both SR 15 and SR 94. At that time, SR 15 is planned be resigned as part of I-15. The remaining portion of SR 15 conforms with Interstate standards.


Junction list

;California : 32nd Street and Norman Scott Road in
Barrio Logan Barrio Logan is a neighborhood in south central San Diego, California. It is bordered by the neighborhoods of East Village and Logan Heights to the north, Shelltown and Southcrest to the east, San Diego Bay to the southwest, and National Cit ...
,
San Diego San Diego ( , ; ) is a city on the Pacific Ocean coast of Southern California located immediately adjacent to the Mexico–United States border. With a 2020 population of 1,386,932, it is the List of United States cities by population, eigh ...
(future interchange) : on the Barrio Logan– SouthcrestLogan Heights, San Diego neighborhood line (future interchange) : on the North ParkCity Heights, San Diego neighborhood line (future interchange) : on the Mission Valley EastGrantville, San Diego neighborhood line : in
Murrieta Murrieta is a city in southwestern Riverside County, California, United States. The population of Murrieta was 110,949 as of the 2020 United States Census, 2020 census. Murrieta experienced a 133.7% population increase between 2000 and 2010, ma ...
: in
Ontario Ontario ( ; ) is one of the thirteen provinces and territories of Canada.Ontario is located in the geographic eastern half of Canada, but it has historically and politically been considered to be part of Central Canada. Located in Central Ca ...
: near
San Bernardino San Bernardino (; Spanish language, Spanish for Bernardino of Siena, "Saint Bernardino") is a city and county seat of San Bernardino County, California, United States. Located in the Inland Empire region of Southern California, the city had a ...
: in Hesperia : in Barstow ;Nevada : in
Enterprise Enterprise (or the archaic spelling Enterprize) may refer to: Business and economics Brands and enterprises * Enterprise GP Holdings, an energy holding company * Enterprise plc, a UK civil engineering and maintenance company * Enterpris ...
: in
Las Vegas Las Vegas (; Spanish for "The Meadows"), often known simply as Vegas, is the 25th-most populous city in the United States, the most populous city in the state of Nevada, and the county seat of Clark County. The city anchors the Las Vegas ...
. I-15/US 93 travels concurrently to northeast of North Las Vegas. ;Arizona : No major intersections ;Utah : south-southwest of
Cove Fort Cove Fort is a fort, unincorporated community, and historical site located in Millard County, Utah. It was founded in 1867 by Ira Hinckley (the paternal grandfather of Gordon B. Hinckley) at the request of Brigham Young. One of its distinctiv ...
: north-northeast of
Holden Holden, formerly known as General Motors-Holden, was an Australian subsidiary company of General Motors. It was an Australian automobile manufacturer, importer, and exporter which sold cars under its own marque in Australia. In its last thre ...
. The highways travel concurrently to Scipio. : in Santaquin. The highways travel concurrently to Spanish Fork. : in Provo : in Lehi. The highways travel concurrently to
Draper Draper was originally a term for a retailer or wholesaler of cloth that was mainly for clothing. A draper may additionally operate as a cloth merchant or a haberdasher. History Drapers were an important trade guild during the medieval period, ...
. : in
Murray Murray may refer to: Businesses * Murray (bicycle company), an American manufacturer of low-cost bicycles * Murrays, an Australian bus company * Murray International Trust, a Scottish investment trust * D. & W. Murray Limited, an Australian who ...
: in
South Salt Lake South Salt Lake is a city in Salt Lake County, Utah, United States and is part of the Salt Lake City Metropolitan Statistical Area. The population was 23,617 at the 2010 census. History Jesse Fox Jr. developed the area South Salt Lake referre ...
. The highways travel concurrently to
Salt Lake City Salt Lake City (often shortened to Salt Lake and abbreviated as SLC) is the Capital (political), capital and List of cities and towns in Utah, most populous city of Utah, United States. It is the county seat, seat of Salt Lake County, Utah, Sal ...
. : in Salt Lake City : in
North Salt Lake North Salt Lake is a city in Davis County, Utah, United States. It is part of the Ogden– Clearfield, Utah Metropolitan Statistical Area. The population was 16,322 at the 2010 census, which had risen to an estimated 20,948 as of 2019. Th ...
: in North Salt Lake : on the West BountifulBountiful city line. The highways travel concurrently to
Farmington Farmington may refer to: Places Canada *Farmington, British Columbia * Farmington, Nova Scotia (disambiguation) United States *Farmington, Arkansas *Farmington, California *Farmington, Connecticut *Farmington, Delaware * Farmington, Georgia * ...
. : in Riverdale. The highways travel concurrently to Tremonton. : on the
Perry Perry, also known as pear cider, is an alcoholic beverage made from fermented pears, traditionally the perry pear. It has been common for centuries in England, particularly in Gloucestershire, Herefordshire, and Worcestershire. It is also mad ...
Brigham City city line. ;Idaho : north-northwest of
Virginia Virginia, officially the Commonwealth of Virginia, is a state in the Mid-Atlantic and Southeastern regions of the United States, between the Atlantic Coast and the Appalachian Mountains. The geography and climate of the Commonwealth ar ...
. The highways travel concurrently to
Pocatello Pocatello () is the county seat of and largest city in Bannock County, with a small portion on the Fort Hall Indian Reservation in neighboring Power County, in the southeastern part of the U.S. state of Idaho. It is the principal city of the P ...
. : northwest of McCammon. The highways travel concurrently to Pocatello. : in Chubbuck : southwest of Blackfoot : in Blackfoot. The highways travel concurrently to
Idaho Falls Idaho Falls ( Shoshoni: Dembimbosaage) is a city in and the county seat of Bonneville County, Idaho, United States. It is the state's largest city outside the Boise metropolitan area. As of the 2020 census, the population of Idaho Falls was 6 ...
. : in Idaho Falls. The highways travel concurrently through Idaho Falls. ;Montana : in
Butte __NOTOC__ In geomorphology, a butte () is an isolated hill with steep, often vertical sides and a small, relatively flat top; buttes are smaller landforms than mesas, plateaus, and tablelands. The word ''butte'' comes from a French word mea ...
. The highways travel concurrently through Butte. : in Butte : in Helena. I-15/US 287 travels concurrently to northeast of Wolf Creek. : in
Great Falls Great may refer to: Descriptions or measurements * Great, a relative measurement in physical space, see Size * Greatness, being divine, majestic, superior, majestic, or transcendent People * List of people known as "the Great" *Artel Great (born ...
. I-15/US 89 travels concurrently to northeast of Vaughn. : in Shelby : at the Sweetgrass-Coutts Border Crossing in the
Canadian border Canadians (french: Canadiens) are people identified with the country of Canada. This connection may be residential, legal, historical or cultural. For most Canadians, many (or all) of these connections exist and are collectively the source of ...
east-northeast of Sweet Grass


Auxiliary routes

*
Inland Empire, California The Inland Empire (IE) is a metropolitan area and region inland of and adjacent to coastal Southern California, centering around the cities of San Bernardino and Riverside, and bordering Los Angeles County to the west. It includes the cities ...
 –
I-215 Interstate 215 is the designation for several Interstate Highways in the United States, all of which are related to Interstate 15 (I-15): * Interstate 215 (California), a regional Interstate bypass for I-15 and a connection to I-10 that serves the ...
*
Henderson, Nevada Henderson is a city in Clark County, Nevada, United States, about southeast of downtown Las Vegas. It is the second largest city in Nevada, after Las Vegas, with an estimated population of 320,189 in 2019. The city is part of the Las Vegas Vall ...
 – I-515 *
Las Vegas, Nevada Las Vegas (; Spanish for "The Meadows"), often known simply as Vegas, is the 25th-most populous city in the United States, the most populous city in the state of Nevada, and the county seat of Clark County. The city anchors the Las Vegas ...
 –
I-215 Interstate 215 is the designation for several Interstate Highways in the United States, all of which are related to Interstate 15 (I-15): * Interstate 215 (California), a regional Interstate bypass for I-15 and a connection to I-10 that serves the ...
*
Salt Lake City, Utah Salt Lake City (often shortened to Salt Lake and abbreviated as SLC) is the Capital (political), capital and List of cities and towns in Utah, most populous city of Utah, United States. It is the county seat, seat of Salt Lake County, Utah, Sal ...
 –
I-215 Interstate 215 is the designation for several Interstate Highways in the United States, all of which are related to Interstate 15 (I-15): * Interstate 215 (California), a regional Interstate bypass for I-15 and a connection to I-10 that serves the ...
*
Butte, Montana Butte ( ) is a consolidated city-county and the county seat of Silver Bow County, Montana, United States. In 1977, the city and county governments consolidated to form the sole entity of Butte-Silver Bow. The city covers , and, according to the ...
 –
I-115 Interstate 115 (I-115) is a auxiliary Interstate Highway which connects I-15/ I-90 to Butte in the U.S. state of Montana. The highway is concurrent with I-15 Bus./ I-90 Bus. for its entire length. The highway travels from an incomplete in ...
*
Great Falls, Montana Great Falls is the third most populous city in the U.S. state of Montana and the county seat of Cascade County. The population was 60,442 according to the 2020 census. The city covers an area of and is the principal city of the Great Falls, M ...
 – I-315


See also

* State Route 15 *
U.S. Route 66 U.S. Route 66 or U.S. Highway 66 (US 66 or Route 66) was one of the original highways in the United States Numbered Highway System. It was established on November 11, 1926, with road signs erected the following year. The h ...
*
U.S. Route 91 U.S. Route 91 or U.S. Highway 91 (US-91) is a north–south United States highway running from Brigham City, Utah, to Idaho Falls, Idaho, in the U.S. states of Idaho and Utah. Despite the "1" as the last digit in the number, US-91 is no lon ...


References


External links

* * https://web.archive.org/web/20030626140609/http://www.dot.ca.gov/dist11/facts/I-15managed.pdf * 2005 Rand McNally ''The Road Atlas 2005''- newest feature- interstate mileage by state ; California
California Highways: SR 15




; Arizona
I-15 Completed December 14, 1973
{{DEFAULTSORT:I15 15 U.S. Route 91