1910 Census microfilms at Internet Archive

Reel 221. Ada and Bannock Counties.
Reel 222. Bear Lake, Blaine, Boise, Bingham, and Blackfoot Counties.
Reel 223. Bonner, Cassia, and Canyon Counties.
Reel 224. Custer, Elmore, Idaho, and Fremont Counties.
Reel 225. Kootenai and Latah Counties.
Reel 226. Lemhi, Lincoln, and Nez Perce Counties.
Reel 227. Oneida, Owyhee, and Shoshone Counties.
Reel 228. Twin Falls and Washington Counties.