Sýslur í Idaho eru 44 talsins.

Nafn Höfuðborg Mannfjöldi (2010) Flatarmál (km2)
Ada Boise 392.365 2.732
Adams Council 3.976 3.535
Bannock Pocatello 82.839 2.883
Bear Lake Paris 5.986 2.515
Benewah St. Maries 9.285 2.010
Bingham Blackfoot 45.607 5.426
Blaine Hailey 21.376 6.851
Boise Idaho City 7.028 4.926
Bonner Sandpoint 40.877 4.501
Bonneville Idaho Falls 104.234 4.841
Boundary Bonners Ferry 10.972 3.287
Butte Arco 2.891 5.783
Camas Fairfield 1.117 2.784
Canyon Caldwell 188.923 1.528
Caribou Soda Springs 6.963 4.574
Cassia Burley 22.952 6.648
Clark Dubois 982 4.571
Clearwater Orofino 8.761 6.377
Custer Challis 4.368 12.758
Elmore Mountain Home 27.038 7.972
Franklin Preston 12.786 1.725
Fremont Saint Anthony 13.242 4.836
Gem Emmett 16.719 1.458
Gooding Gooding 15.464 1.893
Idaho Grangeville 16.267 21.976
Jefferson Rigby 26.139 2.836
Jerome Jerome 22.374 1.554
Kootenai Coeur d'Alene 138.494 3.225
Latah Moscow 37.244 2.789
Lemhi Salmon 7.936 11.821
Lewis Nezperce 3.821 1.241
Lincoln Shoshone 5.208 3.124
Madison Rexburg 37.536 1.222
Minidoka Rupert 20.069 1.968
Nez Perce Lewiston 39.265 2.199
Oneida Malad City 4.286 3.108
Owyhee Murphy 11.526 19.886
Payette Payette 22.623 1.057
Power American Falls 7.817 3.642
Shoshone Wallace 12.765 6.822
Teton Driggs 10.170 1.165
Twin Falls Twin Falls 77.230 4.986
Valley Cascade 9.862 9.668
Washington Weiser 10.198 3.771