# U.S. Route 26 in Idaho

U.S. Highway 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 lanes 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 Interstate 84 (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 toward 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 Business (I-84 Bus.) 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: State Highway 16 (SH-16), SH-55 on the Eagle–Boise city 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 0.75 miles (1.21 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.

### 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 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 Bus., 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 toward 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 Bus.

### 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 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 Bus. Both routes then cross the Snake River (the 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 Bus. branches westward toward 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.

## History

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.
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.

## Major intersections

| County | Location | mi | km | Exit | Destinations | Notes |
| Snake River | Snake River | 0.000 | 0.000 | | US 20 west (East Main Street) / US 26 west – Nyssa | Continuation into Oregon |
| Snake River Bridge; Oregon–Idaho state line ||
| Payette–Canyon county line | ​ | 1.578 | 2.540 | | US 95 north / Anderson Corner Road – Fruitland, Payette | Western end of US 95 overlap |
| Canyon | ​ | 9.647 | 15.525 | | US 95 south – Wilder, Winnemucca | Eastern end of US 95 overlap |
| Canyon | ​ | 21.995– 22.129 | 35.398– 35.613 | 26 | I-84 west / US 30 west / Old Highway 30 – Ontario | Western end of I-84/US 30 overlap; I-84 exit 26 |
| Canyon | Caldwell | 22.858 | 36.786 | 27 | I-84 BL east to SH-19 – Caldwell, Wilder, Homedale | |
| Canyon | Caldwell | 23.755 | 38.230 | 28 | 10th Avenue – Caldwell City Center | |
| Canyon | Caldwell | 24.840– 24.994 | 39.976– 40.224 | 29 | I-84 east / US 30 east / Franklin Road – Caldwell, Boise | Eastern end of I-84/US 30 overlap; I-84 exit 29 |
| Ada | ​ | 34.267 | 55.147 | | SH-16 north (Central Valley Expressway) / North McDermott Road – Emmett | Southern terminus of SH-16 |
| Ada | Boise–Eagle line | 40.229 | 64.742 | | SH-55 (North Eagle Road) – Meridian, Eagle, McCall | |
| Ada | Garden City | 44.166 | 71.078 | | 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 |
| Ada | Boise | 47.290– 47.31 | 76.106– 76.14 | | I-184 west to I-84 | Westbound exit and eastbound entrance; interchange; eastern terminus of I-184 |
| Ada | Boise | 48.050 | 77.329 | | River Street — Bogus Basin | Eastbound exit only; interchange |
| Ada | Boise | 52.135– 52.412 | 83.903– 84.349 | | Federal Way | Interchange |
| Ada | Boise | 52.670– 52.824 | 84.764– 85.012 | 54 | 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) |||||||
| Gooding | ​ | 138.970 | 223.651 | 141 | I-84 east to US 30 – Twin Falls, Bliss, Hagerman | Eastern end of I-84 overlap; Hagerman signed eastbound, Bliss westbound |
| Gooding | Gooding | 150.110 | 241.579 | | SH-46 (Main Street) – Wendell, Fairfield | Hospital signed eastbound only |
| Lincoln | Shoshone | 165.928 | 267.035 | | US 93 south (South Greenwood Street) / South Rail Street East – Twin Falls | Western end of US 93 overlap |
| Lincoln | Shoshone | 165.968 | 267.100 | | SH-75 north (North Greenwood Street) / North Rail Street West – Sun Valley | Southern terminus of SH-75 |
| Blaine | Carey | 204.281 | 328.758 | | 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 |
| Butte | Arco | 248.573 | 400.039 | | US 93 north (North Front Street) / East Grand Avenue – Mackay, Salmon | Eastern end of US 93 overlap; Salmon signed westbound only |
| Butte | ​ | 256.073 | 412.110 | | SH-33 east – Howe | Western terminus of SH-33 |
| Butte | ​ | 272.0 | 437.7 | | US 20 east / East Portland Avenue – Idaho Falls, Idaho National Laboratory | Eastern end of US 20 overlap; laboratory signed westbound only |
| Bingham | ​ | 305.743 | 492.046 | | SH-39 south – Aberdeen | Northern terminus of SH-39 |
| Bingham | Blackfoot | 305.804– 305.893 | 492.144– 492.287 | Snake River | Snake River |
| Bingham | Blackfoot | 305.930– 306.104 | 492.347– 492.627 | 93 | 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) |||||||
| Bonneville | Idaho Falls | 328.980 | 529.442 | 116 | 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 |
| Bonneville | Idaho Falls | 331.102 | 532.857 | | US 91 south (South Yellowstone Avenue) / West Sunnyside Road – Ammon | Northern terminus of US 91; destination signed eastbound only |
| Bonneville | Idaho Falls | 333.044 | 535.982 | | 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 |
| Bonneville | Idaho Falls | 334.374 | 538.123 | | US 20 Bus. north (North Holmes Avenue) / North Holmes Avenue – West Yellowstone | Eastern end of US 20 Bus. overlap |
| Bonneville | Beachs Corner | 338.123– 338.240 | 544.156– 544.345 | | SH-43 north (North Yellowstone Highway) / Ammon Road – Rigby | Southern terminus of SH-43 |
| Bonneville | ​ | 347.787 | 559.709 | | US 26 Bus. east (East Ririe Highway) / North 115th East Road – Rigby, Roberts, Ririe | Western terminus of US 26 Bus.; destinations signed eastbound only |
| Bonneville | ​ | 349.294 | 562.134 | | US 26 Bus. west (130th Road East) to SH-48 – Ririe | Eastern terminus of US 26 Bus. |
| Bonneville | Swan Valley | 376.950 | 606.642 | | SH-31 north – Victor, Driggs | Southern terminus of SH-31 |
| Bonneville | ​ | 402.500 | 647.761 | | US 26 east – Jackson | Continuation into Wyoming |
| 1.000 mi = 1.609 km; 1.000 km = 0.621 mi Concurrency terminus |||||||

## Ririe business route

U.S. Highway 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.
Major intersections
| County | Location | mi | km | Destinations | Notes |
| Bonneville | ​ | 0.000 | 0.000 | US 26 (East Ririe Highway) / North 115th East – Idaho Falls, Pocatello, Swan Valley | Western terminus of US 26 Bus.; continues as North 115th East beyond US 26 |
| Bonneville–Jefferson county line | Ririe | 1.891 | 3.043 | SH-48 west (East County Line Road) – Rigby | Eastern terminus of SH-48 |
| Bonneville | ​ | 2.981 | 4.797 | US 26 – Idaho Falls, Swan Valley, Jackson | Eastern terminus |
| 1.000 mi = 1.609 km; 1.000 km = 0.621 mi ||||||