U.S. Highway 30 (US 30) runs northwest–southeast across the southern half of lower

Idaho Idaho ( ) is a landlocked U.S. state, state in the Pacific Northwest and Mountain states, Mountain West subregions of the Western United States. It borders Montana and Wyoming to the east, Nevada and Utah to the south, and Washington (state), ...

for . US 30 enters the state from

Oregon Oregon ( , ) is a U.S. state, state in the Pacific Northwest region of the United States. It is a part of the Western U.S., with the Columbia River delineating much of Oregon's northern boundary with Washington (state), Washington, while t ...

across the

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

in Fruitland and exits into

Wyoming Wyoming ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States, Western United States. It borders Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho t ...

east of

Dingle Dingle ( or ''Daingean Uí Chúis'', meaning "fort of Ó Cúis") is a town in County Kerry in the south-west of Ireland. The only town on the Dingle Peninsula (known in Irish as ''Corca Dhuibhne''), it sits on the Atlantic Ocean, Atlantic coa ...

. US 30 runs through the large population centers of

Boise Boise ( ) is the capital and most populous city of the U.S. state of Idaho. As of the 2020 census, there were 235,685 people residing in the city. Located on the Boise River in southwestern Idaho, it is east of the Oregon border and nor ...

, Twin Falls, and

Pocatello Pocatello () is the county seat of and the largest city in Bannock County, with a small portion on the Fort Hall Indian Reservation in neighboring Power County, containing the city's airport. It is the principal city of the Pocatello metro ...

, as well as a plethora of smaller communities from Fruitland to Montpelier. The Thousand Springs Scenic Byway is a picturesque section of US 30 in southern Idaho between the towns 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 ...

and Buhl, dipping down into the Hagerman Valley and a canyon of the Snake River. The highway has four extensive concurrencies with Interstate Highways: Interstate 84 (I-84) twice,

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 In ...

, and

I-15 I15 may refer to: * Interstate 15, a north–south Interstate Highway in the United States of America * Polikarpov I-15, a Soviet fighter aircraft * I15 (band), a band * , of the Imperial Japanese Navy * Älvsborg Regiment The Älvsborg Regiment ...

. Outside of its Interstate concurrencies, the route is largely two lanes and rural outside of portions through major towns and cities.

Route description

Oregon state line to Boise

After crossing the Snake River, US 30 enters Fruitland as Northwest 16th Street before intersecting US 95. The route then turns south along US 95 (Whitley Drive in Fruitland). Just north of the I-84 interchange, US 30 turns east toward

New Plymouth New Plymouth () 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, in Devon, from where the first English settlers to New Plymouth migrated. The New Pl ...

. In New Plymouth, US 30 bends south, then southeast, and then south again. Just northeast of the Langley Gulch Power Plant, US 30 begins to travel southeast at a

diamond interchange A diamond interchange is a common type of road junction, used where a controlled-access highway crosses a minor road. Design The freeway itself is grade separation, grade-separated from the minor road, one crossing the other over a bridge. ...

, running concurrently with I-84. Along the way, they serve Sand Hollow with one diamond interchange. Just north of

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

, US 20 and US 26 enter the

freeway A controlled-access highway is a type of highway that has been designed for high-speed vehicular traffic, with all traffic flow—ingress and egress—regulated. Common English terms are freeway, motorway, and expressway. Other similar terms ...

southeastward, joining with the concurrency. Entering Caldwell, they then serve I-84 Business/ State Highway 19 (I-84 Bus./SH-19) and 10th Avenue before both US 20 and US 26 leave the freeway together on Franklin Road. In

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 ...

, I-84 and US 30 then serve SH-55, which then travels eastward concurrently with the two routes. The three routes then serve Northside Boulevard, Franklin Boulevard, and Garrity Boulevard (I-84 Bus.). In Meridian, the freeway concurrency serves

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 Yinchuan–Baise Expressway, G69 Expressway Finland * Finnish national road 69 ...

. At the next exit, SH-55 leaves the concurrency. Then, in Boise, the freeway comes across I-184 which serves

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 U.S. state of Idaho. Economy Largest private sector employers * Note: this list only includes ...

. Between exits 52 and 54, the freeway is situated north adjacent to

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

, with exit 53 serving the main terminal. Also, at exit 54, US 20 and US 26 rejoin the freeway.

Boise to Downtown Pocatello

After leaving Boise, the freeway then serves multiple roads (including SH-21) before reaching Mountain Home. In Mountain Home, the freeway serves I-84 Bus. At the next exit, US 20 leaves the freeway alone. The three remaining routes go on to serve several more roads (such as I-84 Bus. and SH-78). Then, in Bliss, US 30 leaves the freeway and enters the Thousand Springs Scenic Byway. As US 30 approaches I-84, the route turns south and east, serving Hagerman, Buhl,

Filer Filer may refer to: Places * Filer, Idaho * Filer, Missouri * Filer Charter Township, Michigan ** Filer City, Michigan * Filer Haven, a cove on Signy Island, Antarctica * Filer Hill, a mountain near east of Rootville, New York Other * File ...

, and Twin Falls. North of Kimberly, the route then leaves the byway. In Burley, the route then intersects SH-27 and SH-81. In Heyburn, the route rejoins I-84 while also intersecting SH-24. They then serve SH-25/ SH-77 at the same interchange. Then, US 30 transitions from I-84 to I-86 on a modified interchange. Both I-86 and US 30 serve more roads and places (including Register Rock, I-86 Bus., SH-39, and

Pocatello Regional Airport Pocatello Regional Airport is a city-owned, public-use airport in the western United States, located in Power County, Idaho, seven nautical miles (13 km) northwest of central Pocatello. The airport is built on the site of the Pocat ...

). At exit 58, US 30 leaves the freeway as it approaches Pocatello. At this point, US 30 travels along a road parallel to the railroad. Along the way near downtown, it then begins to run concurrently with I-15 Bus. and US 91. Shortly after that, the concurrently splits into a one-way pair.

Thousand Springs Scenic Byway

The Thousand Springs Scenic Byway is a picturesque section of US 30 in southern Idaho between the towns of

and Buhl, dipping down into the Hagerman Valley and a canyon of the

. The byway takes its name from the numerous streams and rivulets springing forth out of the east wall of that canyon, many of them plainly visible from the road, with the panoramic river in the foreground. These springs are outlets from the Snake River Aquifer, which flows through thousands of square miles of porous

volcanic rock Volcanic rocks (often shortened to volcanics in scientific contexts) are rocks formed from lava erupted from a volcano. Like all rock types, the concept of volcanic rock is artificial, and in nature volcanic rocks grade into hypabyssal and me ...

and is one of the largest

groundwater Groundwater is the water present beneath Earth's surface in rock and Pore space in soil, soil pore spaces and in the fractures of stratum, rock formations. About 30 percent of all readily available fresh water in the world is groundwater. A unit ...

systems in the world. The

aquifer An aquifer is an underground layer of water-bearing material, consisting of permeability (Earth sciences), permeable or fractured rock, or of unconsolidated materials (gravel, sand, or silt). Aquifers vary greatly in their characteristics. The s ...

is believed to be fed by the

Big Lost River The Big Lost River is a major river in the U.S. state of Idaho, about long.U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map, accessed May 4, 2011 Description The river starts in the Rocky Mounta ...

which disappears into

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 Natural satellite, moon onto its surface. Lava may be erupted at a volcano or through a Fissure vent, fractu ...

flows near

Arco Arco may refer to: Places * Arco, Trentino, a town in Trentino, Italy * Arco, Idaho, in the United States * Arco, Minnesota, a city in the United States * ARCO Arena in Sacramento, California, home of the Sacramento Kings Companies * ARCO (b ...

, about northeast of Hagerman.

Downtown Pocatello to Wyoming state line

The concurrency returns to a two-way street. It then comes across I-15 at a diamond interchange. At this point, both U.S. Highways continue southeast along I-15 while I-15 Bus. ends there. The three routes (I-15, US 30, and US 91) then serve even more places such as another I-15 Bus. in Inkom. At exit 47, US 30 leaves the freeway to serve McCammon. At this point, US 30 begins to meander across several mountains. Between Alexander and Soda Springs, SH-34 runs concurrently with US 30. US 30 then serves more towns through the rest of the state, especially Montpelier. In Montpelier, US 89 briefly runs concurrently with US 30.

History

US 30 was established in 1926 during the creation of the

United States Numbered Highway System 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 ...

, largely along the transcontinental

Lincoln Highway The Lincoln Highway is one of the first transcontinental highways in the United States and one of the first highways designed expressly for automobiles. Conceived in 1912 by Indiana entrepreneur Carl G. Fisher, and formally dedicated Octob ...

, an existing

auto trail The system of auto trails was an informal network of marked routes that existed in the United States and Canada in the early part of the 20th century. Marked with colored bands on utility poles, the trails were intended to help travellers in t ...

. The corridor was also preceded by the Old Oregon Trail Highway between Oregon and Utah. The highway crossed southern Idaho by following Route 2 between the Oregon state line and Burley, where it split into two suffixed routes: US 30N through Pocatello and to Montpelier; and US 30S toward

Ogden, Utah Ogden ( ) is a city in and the county seat of Weber County, Utah, Weber County, Utah, United States, approximately east of the Great Salt Lake and north of Salt Lake City. The population was 87,321 in 2020, according to the United States Census ...

. Construction of I-80N (now I-84), a freeway that would parallel US 30 between

Portland, Oregon Portland ( ) is the List of cities in Oregon, most populous city in the U.S. state of Oregon, located in the Pacific Northwest region. Situated close to northwest Oregon at the confluence of the Willamette River, Willamette and Columbia River, ...

, and northern Utah, began in the 1960s under the

Federal-Aid Highway Act of 1956 The Federal-Aid Highway Act of 1956, also known as the National Interstate and Defense Highways Act, was enacted on June 29, 1956, when President Dwight D. Eisenhower signed the bill into law. With an original authorization of $25 billion (eq ...

. Various sections of US 30 were relocated onto the new freeway as sections opened over the following two decades. The two suffixed routes were eliminated in 1972 in favor of US 30 remaining on the northern route while generally following I-80N and I-15W (now I-86). A section through Meridian and

was removed in 1980, replaced by a longer overlap with I-84. Five years later, the section from Caldwell to Nampa was replaced with I-84 Bus.

Major intersections

References