List of state highways in Idaho
The Idaho Transportation Department (ITD) is responsible for the establishment and classification of a state highway network, including 5,000 miles (8,000 km) of roads that are classified as Interstate Highways, U.S. Highways, and state highways within the state of Idaho in the United States.[1] The current state highway marker consists of a white background, black numbering, and a solid black geographic outline of the state of Idaho.
   Highway markers for State Highways 3, 75 and 200 | |
| Highway names | |
|---|---|
| Interstates | Interstate X (I-X) |
| US Highways | U.S. Route X (US-X) |
| State | Idaho State Highway X (SH-X) |
| System links | |
| |
History
Scenic state highway marker formerly used on Idaho State Highway 21
During the 1920s, in lieu of numbering its highways, Idaho had a system of lettered Sampson Trails.[2] They were marked by businessman Charles B. Sampson of Boise at no expense to the state, using orange-colored shields.[3] By 1929, the trails system had included 6,500 miles (10,500 km) of marked highways that covered most of the state.[4] By the mid-1930s, the state had adopted a more standard system of numbered state highways.[5][6]
In 1978, the ITD began using brown state highway markers to denote scenic Idaho highways,[7] in addition to the main highway markers that featured a black background and white lettering and the name "IDAHO" in black lettering inside a white geographic outline of the state. The brown markers are no longer used, and in April 2020, ITD changed the coloring of the main state highway marker to its current color scheme, also adding a wide version of the marker for three-digit highways and removing the word "IDAHO" from all markers in the process.[8]
Sampson Trails
The following Sampson Trails were marked:[2]
- A, Boise to Wyoming via Twin Falls and Pocatello; became US‑30 and US‑30N
- B, Boise to Canada via Lewiston and Coeur d'Alene; became US‑30, US‑30N, US‑95, and SH‑1
- C, Pocatello to Montana via Idaho Falls; became US‑91 and US‑191
- D, Boise to New Meadows via Banks; became SH‑15 (today's SH‑55)
- E, not on the 1926 map
- F, Boise to Blackfoot via Stanley; became SH‑21, SH‑17, US‑93 (today's SH‑75), and SH‑27
- G, Mountain Home to Picabo via Fairfield; became SH‑22 (today's US‑20)
- H, Bliss to Trude via Arco; became SH‑24, SH‑23, SH‑22, SH‑29, and an unnumbered road (today's US‑20 and US‑26)
- I, Pioneer to Idaho Falls; became an unnumbered road
- J, Nevada to Shoshone via Twin Falls; became US‑93
- K, Utah to McCammon via Preston; became US‑91
- L, not on the 1926 map
- M, Washington to Montana via Coeur d'Alene; became US‑10
- N, Bonners Ferry to Montana; became US‑2
- O, Oregon to Caldwell; became SH‑49 and SH‑18
- P, Utah to Downey; became SH‑36
- Q, Declo to Fairfield; became SH‑25 and SH‑46
- R, not on the 1926 map
- S, Oregon to Nampa; became unnumbered road and SH‑45
- T, Star to Grimes Pass; became SH‑16, unnumbered road, and SH‑17
- U, Utah to Montpelier; became SH‑35
- V, Hailey to Stanley; became US‑93 (today's SH‑75)
- W, not on the 1926 map
- X, not on the 1926 map
- Y, Bonners Ferry to Canada; became US‑95
State highways
| Number | Length (mi)[9] | Length (km) | Southern or western terminus | Northern or eastern terminus | Formed[10] | Removed | Notes |
|---|---|---|---|---|---|---|---|
 |
12.279 | 19.761 | US‑95 near Copeland | British Columbia Highway 21 at Porthill | 1932 | current | |
|
117.680 | 189.388 | US‑12 near Spalding | I‑90 near Rose Lake | — | — | |
 |
7.380 | 11.877 | I‑90 in Wallace | National Forest Road No. 7623 at Burke | 1926 | current | |
 |
19.140 | 30.803 | US-95 in Plummer | SH‑3 in Saint Maries | — | — | |
 |
40.645 | 65.412 | Washington State Route 272 near Potlatch | SH‑3 near Santa | — | — | |
 |
16.563 | 26.656 | Russell Ridge Road near Orofino | Old Highway 7 in Ahsahka | 1919 | current | |
 |
53.589 | 86.243 | Washington State Route 270 in Moscow | 1st Street in Elk River | — | — | |
 |
13.522 | 21.762 | SH‑8 near Deary | SH‑6 near Harvard | — | — | |
 |
42.481 | 68.367 | US‑12 in Greer | Forest Service Road No. 247 near Headquarters | — | — | |
 |
26.390 | 42.471 | US‑95 in Grangeville | US‑12 near Kooskia | 1919 | current | |
 |
49.515 | 79.687 | SH‑13 near Harpster | Airport Road in Elk City | — | — | |
 |
16.005 | 25.758 | US‑26 near Star | SH‑52 in Emmett | — | — | |
 |
19.915 | 32.050 | Oregon Route 201 near Homedale | I‑84 Business in Caldwell | — | — | |
 |
130.869 | 210.613 | I‑84 in Boise | SH‑75 in Stanley | — | — | |
 |
43.936 | 70.708 | SH‑33 near Howe | I‑15 in Dubois | — | — | |
 |
67.533 | 108.684 | I‑84 / US‑30 in Heyburn | US‑93 in Shoshone | — | — | |
 |
58.048 | 93.419 | I‑84 near Jerome | I‑84 / SH‑77 near Declo | — | — | |
 |
26.561 | 42.746 | Main Street in Oakley | SH‑25 in Paul | — | — | |
 |
135.645 | 218.299 | SH‑33 near Mud Lake | US‑93 in Salmon | 1916 | current | |
 |
13.614 | 21.910 | SH‑28 in Leadore | Montana Secondary Highway 324 at Bannock Pass | — | — | |
 |
21.025 | 33.836 | US‑26 in Swan Valley | SH‑33 in Victor | — | — | |
 |
28.386 | 45.683 | SH‑33 near Tetonia | SH‑47 near Ashton | — | — | |
 |
155.084 | 249.584 | US‑20 / US‑26 near Arco | Wyoming Highway 22 near Victor | — | — | |
 |
105.980 | 170.558 | US‑91 / SH-36 in Preston | Wyoming Highway 239 near Freedom | 1919 | current | |
 |
73.313 | 117.986 | I‑15 near Malad City | US‑89 in Ovid | — | — | |
 |
31.231 | 50.261 | Onedia–Power county line near Holbrook | I‑86 near American Falls | — | — | |
 |
23.438 | 37.720 | North Holbrook Road near Holbrook | I‑15 in Malad City | — | — | |
 |
52.924 | 85.173 | I‑86 in American Falls | US‑26 in Blackfoot | — | — | |
 |
2.737 | 4.405 | I‑15 near Downey | US‑91 in Downey | 1922 | current | |
 |
39.058 | 62.858 | I‑90 in Post Falls | US‑2 in Oldtown | 1931 | current | |
 |
3.868 | 6.225 | US‑26 at Beachs Corner | US‑20 in Ucon | — | — | |
 |
23.089 | 37.158 | I‑84 near Caldwell | US‑20 / US‑26 in Garden City | — | — | |
 |
17.985 | 28.944 | SH‑78 at Walters Ferry | I‑84 Business in Nampa | — | — | |
 |
43.052 | 69.285 | I‑84 near Wendell | US‑20 near Fairfield | — | — | |
 |
12.420 | 19.988 | US‑20 in Ashton | Caribou-Targhee National Forest near Warm River | 1932 | current | |
 |
24.409 | 39.282 | I‑15 near Roberts | US‑26 Business in Ririe | 1930 | current | |
 |
8.092 | 13.023 | US‑30 near Kimberly | SH‑25 near Eden | — | — | |
 |
93.598 | 150.631 | Nevada State Route 225 near Owyhee, Nevada | I‑84 Business in Mountain Home | 1932 | current | |
 |
54.126 | 87.107 | Oregon Route 52 in Payette | SH-55 in Horseshoe Bend | — | — | |
 |
14.255 | 22.941 | Washington State Route 290 near State Line | US‑95 near Hayden | — | — | |
 |
15.440 | 24.848 | SH‑41 in Spirit Lake | Main Avenue in Bayview | — | — | |
 |
156.047 | 251.133 | US‑95 near Marsing | US‑95 in New Meadows | — | — | |
 |
37.230 | 59.916 | US‑2 in Priest River | Reeder Creek Road in Nordman | — | — | |
 |
2.943 | 4.736 | Washington State Route 278 near Rockford, Washington | US‑95 near Worley | — | — | |
 |
5.510 | 8.867 | Washington State Route 274 near Tekoa, Washington | US‑95 near Tensed | — | — | |
 |
0.740 | 1.191 | Wyoming Highway 89 near Geneva | US‑89 in Geneva | — | — | |
 |
15.410 | 24.800 | US‑95 Business in Craigmont | SH‑64 / SH‑162 in Nezperce | — | — | |
 |
15.409 | 24.798 | SH‑62 / SH‑162 in Nezperce | SH‑162 in Kamiah | — | — | |
 |
0.992 | 1.596 | Palouse Cove Road near Palouse, Washington | US‑95 near Viola | — | — | |
 |
8.948 | 14.400 | Mountain Home Air Force Base | SH‑51 in Mountain Home | — | — | |
 |
8.012 | 12.894 | Orchard Avenue in Kuna | I‑84 / US‑30 / SH‑55 in Meridian | — | — | |
 |
28.730 | 46.236 | US‑95 in Cambridge | Oregon Route 86 near Brownlee Dam | — | — | |
 |
1.989 | 3.201 | US‑30 near New Plymouth | SH‑52 at Hamilton Corner | — | — | |
 |
7.835 | 12.609 | US‑93 near Knull | US‑30 in Twin Falls | — | — | |
|
170.666 | 274.660 | US‑26 / US‑93 in Shoshone | US‑93 near Challis | — | — | |
 |
30.676 | 49.368 | SH‑81 in Malta | I‑84 / SH‑25 near Declo | — | — | |
 |
99.720 | 160.484 | SH‑55 in Marsing | I‑84 Business in Hammett | — | — | |
 |
2.564 | 4.126 | I‑84 in Jerome | SH‑25 in Jerome | — | — | |
 |
33.978 | 54.682 | SH‑77 in Malta | US‑30 in Burley | 1972 | current | |
 |
9.133 | 14.698 | US‑20 in Island Park | Montana Highway 87 at Raynolds Pass | — | — | |
 |
35.745 | 57.526 | SH‑3 near Harrison | I‑90 near Coeur d'Alene | — | — | |
 |
11.686 | 18.807 | SH‑3 in Kendrick | SH‑8 in Troy | — | — | |
 |
2.198 | 3.537 | Washington State Route 128 near Lewiston | US‑12 in Lewiston | — | — | |
 |
31.077 | 50.014 | SH‑62 / SH‑64 in Nezperce | US‑12 in Kamiah | — | — | |
 |
16.319 | 26.263 | SH‑78 in Grand View | SH‑67 near Mountain Home Air Force Base | — | — | |
|
33.169 | 53.380 | US‑2 / US‑95 in Ponderay | Montana Highway 200 near Clark Fork | — | — |
References
- "Frequently Asked Questions". Idaho Transportation Department. Retrieved February 15, 2017.
- Rand McNally Auto Road Atlas, 1926, accessed via the Broer Map Library
- Senate Concurrent Resolution No. 8, "a concurrent resolution...to permit Charles B. Sampson to extend the marking system of the Sampson Trail..." passed February 16, 1933
- Lawson, H. A. (March 25, 1929). "Blazing Western Trails is Unique Hobby of Idahoan". Daily Herald. p. 3. Retrieved April 21, 2019 – via Newspapers.com.
- H.M. Gousha Company, Western States road map, published by Standard Oil Company of California, 1935
- Rand McNally and Company, Road map: Idaho, Mont., Wyo., published by Texaco, 1937
- "Colored US highway shields". US ends .com. April 5, 2020. Retrieved April 26, 2020.
- "Traffic Manual: Idaho Supplementary Guidance to the MUTCD" (PDF). Idaho Transportation Department. April 2020. pp. 37–38, 60. Retrieved April 26, 2020.
- "Milepoint Logs". Idaho Transportation Department. Archived from the original on February 16, 2017. Retrieved February 15, 2017.
- Downing, T.A. (April 15, 1937). "Designated Federal and State Highways Minute Book 09". Idaho Bureau of Highways. Retrieved October 3, 2018 – via Idaho State Archives.
External links
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Wikimedia Commons has media related to State highways in Idaho. |
- Idaho Transportation Department
- Road Signs of Idaho (archived April 27, 2004)
- Pend Oreille Scenic Byway
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