U.S. Route 26 in Idaho

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U.S. Highway 26

US 26 highlighted in red
Route information
Maintained by ITD
Length402.5 mi[1] (647.8 km)
Existed1951 (1951)[2]–present
Major junctions
West end US 20 / US 26 near Nyssa, OR
Major intersections
East end US 26 near Alpine, WY
CountryUnited States
CountiesCanyon, Ada, Elmore, Gooding, Lincoln, Blaine, Butte, Bingham, Bonneville
Highway system
  • Idaho State Highway System
SH-25 SH-27

U.S. Route 26 (US 26) runs east–west across south central Idaho for 402.5 miles (647.8 km). US 26 enters the state from Oregon across the Snake River east of Nyssa, Oregon concurrent with US 20 and exits into Wyoming northwest of Alpine. US 26 runs through the large population centers of Boise and Idaho Falls, as well as the smaller communities of Parma, Notus, Garden City, Shoshone, Richfield, Carey, Arco, Blackfoot, Swan Valley, and Irwin.

For a vast majority of its route, US 26 is two-lane and rural, with the exception of portions in and around major towns and cities. It does have significant four-lane segments within the Boise metropolitan area and east of Idaho Falls. Despite its extensive length, US 26 has many hundreds of miles that run concurrently with other highways. In fact, its first 138.97 miles (223.65 km) in the state consists of concurrencies with any one of five different highways, principally US 20 and I-84. It has additional lengthy concurrencies with US 93, US 20 again, and I-15.

US 26 does have one business route in the state of Idaho, which runs through the small community of Ririe northeast of Idaho Falls.

Route description

Oregon state line to Downtown Boise

After crossing the Snake River at the Oregon state line, US 26 and US 20 make a curve towards US 95. At that point, both routes travel south along US 95. The three routes then travel south and then curves southeast in Parma. Then, US 95 branches southward while the rest continues southeast. Both US 26 and US 20 pass through Notus before meeting I-84/US 30. At this point, the four routes meet I-84 BL and then 10th Avenue before US 20 and US 26 travel east on Franklin Road; all of the exits are in Caldwell.

As the two routes approach Boise, they intersect three state highways: SH-16, SH-55 in Eagle–Boise line, and SH-44 in Garden City. In Boise, as US 26 and US 20 merge eastward onto I-184, the interstate designation ends there but the freeway ends in about 34 mile (1.2 km). Just after the freeway crosses the Boise River, both routes traveling eastbound serve River Street and Bogus Basin. After this, the freeway approaches a 45 mph (72 km/h) curve and then becomes an at-grade one-way pair.[3]

Downtown Boise to Blackfoot

As both routes exit downtown, they turn south and become a two-way street. Also, the two routes cross the Boise River for the second time. After that, they run along the eastern edge of the Boise State University. As they approach Boise Airport, they then turn east onto I-84/US 30 again. This time, US 26 runs concurrently with I-84 for about 87 miles (140 km). Along the way, the freeway serves several state highways, I-84 Business Loops, and local roads in different locations. At one point east of Mountain Home, US 20 leaves the freeway and travels northeastward. As the freeway reaches Bliss, US 30, along with I-84 BL, leaves the freeway as Thousand Springs Scenic Byway. At the next exit, US 26 leaves the freeway.

US 26 went on to serve a handful of state highways in Gooding and Shoshone. Also in Shoshone, the route begins to run concurrently with US 93. Both routes then serve Richfield. In Carey, they begin to run concurrently with US 20. For US 26, this is the second time in Idaho. The three routes serve Craters of the Moon National Monument and Preserve and Blizzard Mountain Ski Area. In Arco, US 93 branches northwestward. The rest continues eastward through Butte City and serving SH-33. Just southeast of the base of Idaho National Laboratory, US 26 branches southeast towards Blackfoot while US 20 continues east. As US 26 approaches Blackfoot, the route intersects SH-39 and then crosses over the same Snake River. Shortly after that, it turns northeast onto I-15 while the road continues as I-15 BL.[3]

Blackfoot to Wyoming state line

At this point, US 26 begins to run concurrently with I-15 for the next 23 miles (37 km). All of the interchanges within this concurrency lead to local roads. As the freeway enters Idaho Falls, US 26 leaves the freeway and turns east along I-15 BL. Both routes then cross the Snake River (third time for US 26) and then intersect the northern terminus of US 91. At this point, both travel north toward downtown Idaho Falls. In downtown, I-15 BL branches westward towards I-15/US 20. Continuing northeast, US 26 intersects several more routes: SH-43 in Beachs Corner, US 26 Bus. (twice) near Ririe, and SH-31 in Swan Valley. Continuing eastward, US 26 travels along the bank of Snake River and then enters Wyoming.[3]


When US 26 was initially designated in the state in 1951, it ran only as far west as Idaho Falls. The next year, it was extended into Oregon.[2]

In the Idaho Falls area, US 26 runs along local streets and county roads. In 2022, the Idaho Transportation Board approved a study into relocating parts of the highway onto US 20 following the reconstruction of the I-15/US 20 interchange at the west end of the Rigby Freeway.[4]

Major intersections


US 20 west (East Main Street) / US 26 west – Nyssa
Continuation into Oregon
US 95 north / Anderson Corner Road – Fruitland, Payette
Western end of US 95 overlap
US 95 south – Wilder, Winnemucca
Eastern end of US 95 overlap

I-84 west / US 30 west / Old Highway 30 – Ontario
Western end of I-84/US 30 overlap; I-84 exit 26

I-84 BL east to SH-19 – Caldwell, Wilder, Homedale
23.75538.2302810th Avenue – Caldwell City Center

I-84 east / US 30 east / Franklin Road – Caldwell, Boise
Eastern end of I-84/US 30 overlap; I-84 exit 29
SH-16 north (Central Valley Expressway) / North McDermott Road – Emmett
Southern terminus of SH-16
BoiseEagle line40.22964.742 SH-55 (North Eagle Road) – Meridian, Eagle, McCall
Garden City44.16671.078

SH-44 west (North Glenwood Street) to SH-55 / North Glenwood Street – Eagle, McCall
Eastern terminus of SH-44; to SH-55 signed westbound only

I-184 west to I-84
Westbound exit and eastbound entrance; interchange; eastern terminus of I-184
48.05077.329River Street —  Bogus BasinEastbound exit only; interchange
Federal WayInterchange

I-84 west / US 30 west / Commerce Avenue – Nampa
Western end of I-84/ US30 overlap; I-84 exit 54
See I-84 (see mile 54.485–140.405)

I-84 east to US 30 – Twin Falls, Bliss, Hagerman
Eastern end of I-84 overlap; Hagerman signed eastbound, Bliss westbound
Gooding150.110241.579 SH-46 (Main Street) – Wendell, FairfieldHospital signed eastbound only
US 93 south (South Greenwood Street) / South Rail Street East – Twin Falls
Western end of US 93 overlap
SH-75 north (North Greenwood Street) / North Rail Street West – Sun Valley
Southern terminus of SH-75
US 20 west (Queen Crown Road) / Cenarrusa Lane – Picabo, Sun Valley, Boise
Western end of US 20 overlap; Picabo signed northbound, Sun Valley and Boise southbound
US 93 north (North Front Street) / East Grand Avenue – Mackay, Salmon
Eastern end of US 93 overlap; Salmon signed westbound only
SH-33 east – Howe
Western terminus of SH-33
US 20 east / East Portland Avenue – Idaho Falls, Idaho National Laboratory
Eastern end of US 20 overlap; laboratory signed westbound only
SH-39 south – Aberdeen
Northern terminus of SH-39
Snake River

I-15 south / I-15 BL south – Pocatello, Blackfoot
Western end of I-15 overlap; northern terminus of I-15 Bus.; I-15 exit 93
See I-15 (mile 92.734–115.610)
BonnevilleIdaho Falls328.980529.442116
I-15 north / West 33rd South – Idaho Falls, Butte
Eastern end of I-15 overlap; western end of I-15 Bus. overlap; southern terminus of I-15 Bus.; I-15 exit 116
US 91 south (South Yellowstone Avenue) / West Sunnyside Road – Ammon
Northern terminus of US 91; destination signed eastbound only

I-15 BL north / US 20 Bus. west (West Broadway Street) to I-15 / Elm Street – Butte, Arco
Eastern end of I-15 Bus. overlap; western end of US 20 Bus. overlap; To I-15, Butte signed eastbound only

US 20 Bus. north (North Holmes Avenue) / North Holmes Avenue – West Yellowstone
Eastern end of US 20 Bus. overlap
Beachs Corner338.123–

SH-43 north (North Yellowstone Highway) / Ammon Road – Rigby
Southern terminus of SH-43

US 26 Bus. east (East Ririe Highway) / North 115th East Road – Rigby, Roberts, Ririe
Western terminus of US 26 Bus.; destinations signed eastbound only

US 26 Bus. west (130th Road East) to SH-48 – Ririe
Eastern terminus of US 26 Bus.
Swan Valley376.950606.642
SH-31 north – Victor, Driggs
Southern terminus of SH-31
US 26 east – Jackson
Continuation into Wyoming
1.000 mi = 1.609 km; 1.000 km = 0.621 mi

Ririe business route

Business plate.svg

U.S. Highway 26 Business

Length2.981 mi[1] (4.797 km)

U.S. Route 26 Business (US 26 Bus.) is a 2.981-mile-long (4.797 km) business route in and around the small town of Ririe northeast of Idaho Falls. It connects US 26 to the community as well as SH-48.

Bonneville0.0000.000 US 26 (East Ririe Highway) / North 115th East – Idaho Falls, Pocatello, Swan ValleyWestern terminus of US 26 Bus.; continues as North 115th East beyond US 26
county line
SH-48 west (East County Line Road) – Rigby
Eastern terminus of SH-48
Bonneville28.98146.640 US 26 – Idaho Falls, Swan Valley, JacksonEastern terminus
1.000 mi = 1.609 km; 1.000 km = 0.621 mi


  1. ^ a b c d "State Highway System Route: 0026" (PDF). Idaho Transportation Department Milepoint Log. Idaho Transportation Department. January 25, 2016. Retrieved November 7, 2020.
  2. ^ a b Elbert, Chris; et al. (October 7, 2020). "ern end of US Highway 26". USEnds.com. Retrieved November 7, 2020.
  3. ^ a b c Google (August 6, 2021). "Overview map of US 26 in Idaho" (Map). Google Maps. Google. Retrieved August 6, 2021.
  4. ^ "Idaho Transportation Board Subcommittee on State Highway System Adjustments, September 21, 2022" (PDF). Idaho Transportation Department. September 21, 2022. p. 12. Retrieved February 12, 2023.
  5. ^ "State Highway System Route: 0020" (PDF). Idaho Transportation Department Milepoint Log. Idaho Transportation Department. January 25, 2016. Retrieved November 5, 2020.
  6. ^ "State Highway System Route: 0093" (PDF). Idaho Transportation Department Milepoint Log. Idaho Transportation Department. January 12, 2016. Retrieved November 6, 2020.
  7. ^ "State Highway System Route: 0015" (PDF). Idaho Transportation Department Milepoint Log. Idaho Transportation Department. January 25, 2016. Retrieved November 7, 2020.