List of state highways in Idaho

History

Sampson Trails

• 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
• E, not on the 1926 map
• F, Boise to Blackfoot via Stanley; became SH‑21, SH‑17, US‑93, and SH‑27
• G, Mountain Home to Picabo via Fairfield; became SH‑22
• H, Bliss to Trude via Arco; became SH‑24, SH‑23, SH‑22, SH‑29, and an unnumbered road
• 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
• W, not on the 1926 map
• X, not on the 1926 map
• Y, Bonners Ferry to Canada; became US‑95

  State highways