Interstate 84 (I-84) in the U.S. state of

Idaho Idaho ( ) is a U.S. state, 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 Monta ...

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. T ...

that traverses the state from the

Oregon Oregon () is a U.S. state, state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington (state), Washington, while the Snake River delineates much of it ...

state line in the northwest to

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 its ...

state line in the southeast. It primarily follows the

Snake River The Snake River is a major river of the greater Pacific Northwest region in the United States. At long, it is the largest tributary of the Columbia River, in turn, the largest North American river that empties into the Pacific Ocean. The Snake ...

across a

plain In geography, a plain is a flat expanse of land that generally does not change much in elevation, and is primarily treeless. Plains occur as lowlands along valleys or at the base of mountains, as coastal plains, and as plateaus or uplands ...

that includes the cities of

Boise 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 area' ...

, Mountain Home, and Twin Falls. The highway is one of the busiest in Idaho and is designated as the Vietnam Veterans Memorial Highway. I-84 runs for within Idaho, beginning near

Ontario, Oregon Ontario is the largest city in Malheur County, Oregon, United States. It lies along the Snake River at the Idaho border. The population was 11,366 at the 2010 census. The city is the largest community in the region of far eastern Oregon, also k ...

, and traveling concurrent with several

U.S. routes The United States Numbered Highway System (often called U.S. Routes or U.S. Highways) is an integrated network of roads and highways numbered within a nationwide grid in the contiguous United States. As the designation and numbering of these hi ...

through the

Boise metropolitan area The Boise–Nampa, Idaho Metropolitan Statistical Area (MSA) (commonly known as the Boise Metropolitan Area or the Treasure Valley) is an area that encompasses Ada, Boise, Canyon, Gem, and Owyhee counties in southwestern Idaho, anchored by the ...

and Mountain Home towards Twin Falls. I-84 splits away from US 30 and the Snake River at a junction 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 ...

near Declo, where it turns southeast to cross the

Sublett Range The Sublett Range is a mountain range in the U.S. states of Idaho (~94%) and Utah (~6%), spanning Cassia, Oneida, and Power counties, Idaho and reaching into Box Elder County, Utah. The Phosphoria Formation reaches its greatest thickness beneath ...

into northern Utah. The highway has an auxiliary route,

I-184 Interstate 184 (I-184) is a short auxiliary Interstate Highway in Boise, Idaho, United States. It is a spur route of I-84 that connects the freeway to Downtown Boise, terminating at US Highway 20 (US 20) and US 26. Rout ...

, which serves downtown Boise.

Route description

I-84 is the longest Interstate highway in Idaho, running for and connecting several of the state's largest metropolitan areas. It has a single auxiliary route,

in Boise, and several

business routes A business route (or business loop, business spur, or city route) in the United States is a short special route connected to a ''parent'' numbered highway at its beginning, then routed through the central business district of a nearby city ...

. The highway was officially designated as the Vietnam Veterans Memorial Highway in 2014, mirroring the name for Oregon's section of I-84."Idaho S1227: " The Idaho section of I-84 is maintained by the

Idaho Transportation Department The Idaho Transportation Department (ITD) is the state of Idaho governmental organization responsible for state transportation infrastructure. This includes ongoing operations and maintenance as well as planning for future needs of the state and i ...

(ITD), which conducts an annual survey of traffic on certain highway segments that is expressed in terms of

average annual daily traffic Annual average daily traffic, abbreviated AADT, is a measure used primarily in transportation planning, transportation engineering and retail location selection. Traditionally, it is the total volume of vehicle traffic of a highway or road for a ...

(AADT), a measure of traffic volume for any average day of the year. Average daily traffic volumes on I-84 in 2018 ranged from a minimum of 9,552 vehicles near Sweetzer Summit and 139,113 vehicles at I-184 in western Boise.

Boise and Treasure Valley

I-84 enters the state of Idaho after crossing the

from

, west of

Fruitland, Idaho Fruitland is a city along the Snake and Payette rivers in Payette County, Idaho, United States. It lies along U.S. Route 95 in the Treasure Valley of southwest Idaho, about west of Boise on the border with Oregon. It is part of the Ontario ...

. The four-lane freeway travels southeast along the Snake River and passes an eastbound-only

rest area A rest area is a public facility located next to a large thoroughfare such as a motorway, expressway, or highway, at which drivers and passengers can rest, eat, or refuel without exiting onto secondary roads. Other names include motorway serv ...

and

visitors center A visitor center or centre (see American and British English spelling differences), visitor information center, tourist information center, is a physical location that provides tourist information to visitors. Types of visitor center A visit ...

, which mirrors a westbound facility on the Oregon side of the river. Its first interchange is with US 95, the primary north–south highway in Idaho, at Palisades Corner south of Fruitland. I-84 continues southeast across farmland in the

Snake River Plain The Snake River cutting through the plain leaves many canyons and Canyon#List of gorges">gorges, such as this one near Twin Falls, Idaho The Snake River Plain is a geologic feature located primarily within the U.S. state of Idaho. It stre ...

and straddles the edge of a hill. South of

New Plymouth New Plymouth ( mi, Ngāmotu) is the major city of the Taranaki region on the west coast of the North Island of New Zealand. It is named after the English city of Plymouth, Devon from where the first English settlers to New Plymouth migrated. Th ...

the freeway intersects and becomes concurrent with US 30. The paired highways continue south along the side of a hill and cross into Canyon County northeast of Notus. The freeway enters the Treasure Valley, which also constitutes much of the

, near the outskirts of

Caldwell Caldwell may refer to: People * Caldwell (surname) * Caldwell (given name) * Caldwell First Nation, a federally recognized Indian band in southern Ontario, Canada Places Great Britain * Caldwell, Derbyshire, a hamlet * Caldwell, Eas ...

and intersects State Highway 44 (SH-44), which continues east to Middleton and

Eagle Eagle is the common name for many large birds of prey of the family Accipitridae. Eagles belong to several groups of genera, some of which are closely related. Most of the 68 species of eagle are from Eurasia and Africa. Outside this area, j ...

. Shortly before crossing the

Boise River The Boise River is a U.S. Geological Survey. National Hydrography Dataset high-resolution flowline data. , accessed May 3, 2011 tributary of the Snake River in the Northwestern United States. It drains a rugged portion of the Sawtooth Range in sou ...

into Downtown Caldwell, I-84 and US 30 begin a brief concurrency with US 20 and US 26, with both continue west towards

Parma Parma (; egl, Pärma, ) is a city in the northern Italian region of Emilia-Romagna known for its architecture, music, art, prosciutto (ham), cheese and surrounding countryside. With a population of 198,292 inhabitants, Parma is the second m ...

and the Oregon state border. The freeway skirts the north side of Downtown Caldwell, which is served by a designated

business route A business route (or business loop, business spur, or city route) in the United States is a short special route connected to a ''parent'' numbered highway at its beginning, then routed through the central business district of a nearby city ...

, and passes through residential neighborhoods before US 20 and US 26 split off and travel east onto Franklin Road. I-84 and US 30 continue southeast through an industrial area and pass the Caldwell Industrial Airport and Karcher Mall before reaching the city of

Nampa The Namibia Press Agency (NAMPA) is the national news agency of the Republic of Namibia. It was founded in 1987 under the name Namibia Press Association as a SWAPO partisan press agency, and resuscitated after independence under its current name ...

. The freeway travels through an industrial area on the northwestern side of Nampa, parallel to a set of railroad tracks, but turns east to bypass the city center. SH-55 joins the concurrency at an interchange with Karcher Road and I-84 Business returns to the freeway at an interchange located near Nampa Gateway Center, the Nampa campus of the

College of Western Idaho College of Western Idaho (CWI) is a public community college in Southwest Idaho with its primary campus locations in Boise and Nampa. CWI also offers classes at several community locations throughout the Treasure Valley. It is one of four compr ...

, and the

Ford Idaho Center The Ford Idaho Center is a complex of sports and entertainment venues in Nampa, Idaho, approximately west of Boise. About The Ford Idaho Center Arena is best known for rodeo. It annually hosts the Snake River Stampede, considered one of the na ...

. I-84 expands from four lanes to eight lanes as it leaves Nampa and enters Ada County, passing through suburban neighborhoods in Meridian. The freeway crosses under two

single-point urban interchange A single-point urban interchange (SPUI, or ), also called a single-point interchange (SPI) or single-point diamond interchange (SPDI), is a type of highway interchange. The design was created in order to help move large volumes of traffic thr ...

s at Ten Mile Road and

SH-69 Route 69, or Highway 69, may refer to: International * European route E69 Australia * Appin Road Canada * Alberta Highway 69 * Ontario Highway 69 China * G69 Expressway Finland * Finnish national road 69 India * National Highway 69 (In ...

, along with a

partial cloverleaf interchange A partial cloverleaf interchange or parclo is a modification of a cloverleaf interchange. The design has been well received, and has since become one of the most popular freeway-to- arterial interchange designs in North America. It has also be ...

where SH-55 splits from the concurrency to head north. I-84 enters the city of

and expands to ten lanes before an interchange with

, an auxiliary route that travels into

Downtown Boise Downtown Boise is the central business district of Boise, Idaho, Boise, Idaho, located north of the Boise River. It is the largest city center in the state of Idaho. Economy Largest private sector employers * Note: this list only includes compa ...

. I-84 turns southeast and travels around the city's outer residential neighborhoods, passing the main terminal at

Boise Airport Boise Airport (Boise Air Terminal or Gowen Field) is a joint civil-military airport in the western United States, south of downtown Boise in Ada County, Idaho. The airport is operated by the city of Boise Department of Aviation and is oversee ...

and a nearby industrial area. The freeway is rejoined by US 20 and US 26 before leaving Boise, climbing out of Treasure Valley by following Fivemile Creek over a barren plateau.

Mountain Home and Magic Valley

The highway crosses into Elmore County and rejoins the

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 ...

's Nampa Subdivision as it passes the

Morley Nelson Snake River Birds of Prey National Conservation Area The Morley Nelson Snake River Birds of Prey National Conservation Area has one of the densest populations of nesting raptors. The National Conservation Area (NCA) is located south of Boise, Idaho along of the Snake River, and is managed by the ...

. I-84 then travels around the city of Mountain Home, while a signed business route serves the city center and leads to the nearby

Mountain Home Air Force Base Mountain Home Air Force Base is a United States Air Force (USAF) installation in the western United States. Located in southwestern Idaho in Elmore County, the base is southwest of Mountain Home, which is southeast of Boise via Interstat ...

. On the east side of the city, I-84 intersects SH-51 and ends its concurrency with US 20, which continues east towards Sun Valley,

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

Yellowstone National Park 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 Yellowst ...

. I-84, US 26, and US 30 continue southeast through the conservation area and descends from the plateau into the

. The freeway travels around the north side of Hammett, which is served by a

that connects to SH-78, and reaches the Snake River. I-84 travels upstream along the north bank of the Snake River to Glenns Ferry, where it bypasses the town and Three Island Crossing State Park. The freeway crosses over the river twice east of Glenns Ferry to avoid a bend in the river, which is followed by the railroad. After entering Gooding County, I-84 reaches the town of

Bliss BLISS is a system programming language developed at Carnegie Mellon University (CMU) by W. A. Wulf, D. B. Russell, and A. N. Habermann around 1970. It was perhaps the best known system language until C debuted a few years later. Since then, C b ...

, where US 30 and US 26 both split from the freeway and end their concurrency. US 30 travels south along the Snake River towards Hagerman, while US 26 runs east across the plains to Gooding and

Craters of the Moon National Monument and Preserve Craters of the Moon National Monument and Preserve is a U.S. national monument and national preserve in the Snake River Plain in central Idaho. It is along US 20 ( concurrent with US 93 and US 26), between the small towns of Arco and Carey, a ...

. The freeway continues southeast and crosses over the Mallad Gorge (part of

Thousand Springs State Park Thousand Springs State Park is a public recreation and nature preservation area consisting of multiple units — Billingsley Creek, Earl M. Hardy Box Canyon Springs Nature Preserve, Malad Gorge, Niagara Springs, and Ritter Island — in Gooding C ...

) on a pair of level bridges. I-84 then passes through farmland on the edge of a lava plain while following an abandoned railroad

right of way Right of way is the legal right, established by grant from a landowner or long usage (i.e. by prescription), to pass along a specific route through property belonging to another. A similar ''right of access'' also exists on land held by a gov ...

to Wendell, where it intersects SH-46. The freeway travels around the south side of Wendell and turns east to follow an active railroad through a rural area that marks the boundary of Jerome County. I-84 reaches the county seat, also named

Jerome Jerome (; la, Eusebius Sophronius Hieronymus; grc-gre, Εὐσέβιος Σωφρόνιος Ἱερώνυμος; – 30 September 420), also known as Jerome of Stridon, was a Christian priest, confessor, theologian, and historian; he is co ...

, and turns southeast after intersecting SH-25 to bypass the city. The interstate intersects SH-79 on the south side of Jerome and reaches a partial cloverleaf interchange with US 93 across the Snake River Canyon from the city of Twin Falls. I-84 then proceeds eastward through the rural

Magic Valley The Magic Valley is a region in south-central Idaho constituting Blaine, Camas, Cassia, Gooding, Jerome, Lincoln, Minidoka, and Twin Falls counties. It is particularly associated with the agricultural region in the Snake River Plain located ...

, staying on the north side of the Snake River. It intersects SH-50 at Tipperary Corner and bends south around Skeleton Butte and a municipal airport in Hazelton. Between Hazelton and the Minidoka County line, I-84 is concurrent with SH-25, which continues along the north side of the valley.

Southeastern Idaho

I-84 passes north of Burley, intersecting SH-27 near

Paul Paul may refer to: *Paul (given name), a given name (includes a list of people with that name) * Paul (surname), a list of people People Christianity *Paul the Apostle (AD c.5–c.64/65), also known as Saul of Tarsus or Saint Paul, early Chri ...

. At a partial cloverleaf interchange in northeastern Heyburn, the freeway intersects SH-24 and is rejoined by US 30, beginning a new concurrency as the highway leaves the Magic Valley. I-84 crosses over the Snake River into Cassia County and intersects SH-25 and SH-25 at an interchange on the east bank of the river near Declo. Near the Minidoka National Wildlife Refuge, I-84 reaches the western terminus of

, which carries US 30 and follows the Snake River upstream to

American Falls The American Falls is the second-largest of the three waterfalls that together are known as Niagara Falls on the Niagara River along the Canada–U.S. border. Unlike the much larger Horseshoe Falls, of which approximately 90% is in Ontari ...

and

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 ...

. I-84 turns southeast from the interchange and continues into the Raft River Valley, running parallel to SH-81 near Horse Butte in view of the Cotterel Mountains. After crossing the rural valley, I-84 begins following Meadow Creek and climbs into Mortenson Canyon, which marks the northeastern extent of the

Black Pine Mountains The Black Pine Mountains are a mountain range in the U.S. states of Idaho (~65%) and Utah (~35%), spanning Cassia County, Idaho and reaching into Box Elder County, Utah. The highest point in the range is known as Black Pine Mountains High Point, ...

. The highway crests at Sweetzer Summit, located above sea level, and descends into the Juniper Valley on the south side of the

Sawtooth National Forest Sawtooth National Forest is a National Forest that covers 2,110,408 acres (854,052 ha) in the U.S. states of Idaho (~96 percent) and Utah (~4 percent). Managed by the U.S. Forest Service in the U.S. Department of Agriculture, it was originall ...

. I-84 continues southeast across the valley, passing a set of

s in Oneida County, and reaches the

state border northwest of Snowville. The freeway continues into Utah and passes through Ogden before terminating at a junction 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 ...

in 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 ...

History

Prior to the construction of I-84, the corridor was served by Idaho State Highway 2 and Route A of the Sampson Trails system.

U.S. Route 30 U.S. Route 30 or U.S. Highway 30 (US 30) is an east–west main route in the system of the United States Numbered Highways, with the highway traveling across the northern tier of the country. With a length of , it is the third longest ...

was created in 1926 under the national numbered highway system, traveling through southern Idaho along the historic

Oregon Trail The Oregon Trail was a east–west, large-wheeled wagon route and emigrant trail in the United States that connected the Missouri River to valleys in Oregon. The eastern part of the Oregon Trail spanned part of what is now the state of Kans ...

. Near Declo, US 30 split into two routes: U.S. Route 30N, following the Snake River to Pocatello, and

U.S. Route 30S U.S. Route 30S may refer to: * U.S. Route 30S (Oregon), now OR 201 and US 20/US 26 from Ontario to Caldwell * U.S. Route 30S (Idaho–Utah–Wyoming), now I-84 and I-80 from Burley to Granger * U.S. Route 30S (Nebraska–Iowa), now US 275, US 6, and ...

, providing a shorter connection to the

Salt Lake City Salt Lake City (often shortened to Salt Lake and abbreviated as SLC) is the capital and most populous city of Utah, United States. It is the seat of Salt Lake County, the most populous county in Utah. With a population of 200,133 in 2020, th ...

area. The Interstate highway was initially designated in 1957 as Interstate 82, but was renumbered as Interstate 80N in 1958 to correspond with US 30. It remained as Interstate 80N until May 1, 1980, when it was changed to Interstate 84 to eliminate confusion with the western section of the non-suffixed I-80, which split from I-80N in Salt Lake City and continued west to

San Francisco San Francisco (; Spanish for " Saint Francis"), officially the City and County of San Francisco, is the commercial, financial, and cultural center of Northern California. The city proper is the fourth most populous in California and 17t ...

. The route of I-80N between Nampa and Boise was selected in 1958 as one of eight proposals and completed in stages between 1965 and 1968. Rural sections in southwestern Idaho had already been completed by the mid-1960s, connecting

, to Caldwell, and Boise to Mountain Home. The Nampa–Meridian section opened to traffic on September 29, 1965. Another from SH-69 in Meridian to western Boise opened on December 12, 1968, at a cost of $9.5 million. The freeway was extended west from Nampa to Caldwell on December 21, 1966, filling a gap in Interstate 80N and connecting to an already-completed rural section. The bypass around southeastern Boise was opened in November 1969 and cost $6.5 million to construct. Another section was opened around the same time in Sublett in eastern Cassia County, which caused the killing of eighteen

mule deer The mule deer (''Odocoileus hemionus'') is a deer indigenous to western North America; it is named for its ears, which are large like those of the mule. Two subspecies of mule deer are grouped into the black-tailed deer. Unlike the related whi ...

from a local herd from collisions with drivers within the first six weeks. Several rest areas on I-84 were closed in 1992 due to budget cuts and maintenance issues and their restoration was dependent on several federal highway bills that were never passed. To address increasing traffic congestion in the Boise metropolitan area, fueled by population growth and suburban development, the

(ITD) has widened sections of I-84 in recent years. A section between eastern Nampa and Meridian was widened to six lanes in October 2009 and eight lanes in August 2011 as part of a $113 million expansion program. The agency has also built several

s in Meridian and Boise to improve efficiency. The section through Nampa is planned to be widened to six lanes by 2021 at a cost of $150 million. In 2017, the ITD also began work to resurface and restore fifteen bridges on I-84 that had deteriorated over their lifespan. The project also included pavement repair and improvements on of the highway in the

region. In 2014 and 2019, because of increased speeds and the installation of new interchanges at Declo and Twin Falls, the ITD closed the Jerome rest area and extended the Cotterell rest area to make way for a new weigh station. To remedy this Idaho joined the Interstate Oasis Program and opened three truck stops in Twin Falls and Jerome.

Exit list

References

External links