| County | Constitution | Democratic | Libertarian | Republican | Unaffiliated | Total Registered |
|---|---|---|---|---|---|---|
| Ada | 596 | 38,162 | 2,534 | 95,391 | 97,429 | 234,112 |
| Adams | 15 | 174 | 15 | 1,679 | 647 | 2,530 |
| Bannock | 128 | 4,449 | 374 | 17,320 | 18,188 | 40,459 |
| Bear Lake | 16 | 108 | 7 | 2,571 | 604 | 3,306 |
| Benewah | 30 | 525 | 27 | 2,302 | 2,155 | 5,039 |
| Bingham | 77 | 1,433 | 73 | 11,829 | 5,643 | 19,055 |
| Blaine | 10 | 2,640 | 102 | 3,171 | 6,729 | 12,652 |
| Boise | 22 | 329 | 35 | 2,844 | 1,352 | 4,582 |
| Bonner | 156 | 2,297 | 218 | 13,794 | 8,187 | 24,652 |
| Bonneville | 153 | 3,639 | 363 | 29,799 | 17,172 | 51,126 |
| Boundary | 24 | 416 | 49 | 4,079 | 1,525 | 6,093 |
| Butte | 5 | 58 | 5 | 1,154 | 262 | 1,484 |
| Camas | 5 | 30 | 5 | 457 | 184 | 681 |
| Canyon | 401 | 8,719 | 748 | 44,946 | 31,089 | 85,903 |
| Caribou | 20 | 97 | 10 | 2,693 | 831 | 3,651 |
| Cassia | 28 | 450 | 32 | 6,745 | 2,032 | 9,287 |
| Clark | 2 | 17 | 2 | 314 | 51 | 386 |
| Clearwater | 9 | 368 | 24 | 2,253 | 1,700 | 4,354 |
| Custer | 4 | 140 | 15 | 1,964 | 673 | 2,796 |
| Elmore | 32 | 919 | 74 | 5,691 | 3,319 | 10,035 |
| Franklin | 37 | 164 | 28 | 4,621 | 1,264 | 6,114 |
| Fremont | 31 | 265 | 19 | 4,906 | 1,441 | 6,662 |
| Gem | 46 | 581 | 53 | 6,129 | 2,591 | 9,400 |
| Gooding | 22 | 517 | 33 | 3,761 | 1,783 | 6,116 |
| Idaho | 38 | 533 | 54 | 6,612 | 2,360 | 9,597 |
| Jefferson | 41 | 392 | 48 | 9,913 | 2,817 | 13,211 |
| Jerome | 125 | 649 | 37 | 4,417 | 2,699 | 7,927 |
| Kootenai | 319 | 8,150 | 610 | 42,404 | 26,017 | 77,500 |
| Latah | 84 | 4,174 | 298 | 7,619 | 9,621 | 21,796 |
| Lemhi | 10 | 355 | 22 | 3,210 | 1,160 | 4,757 |
| Lewis | 9 | 135 | 7 | 1,159 | 678 | 1,988 |
| Lincoln | 7 | 162 | 14 | 1,338 | 591 | 2,112 |
| Madison | 84 | 516 | 163 | 12,986 | 4,414 | 18,163 |
| Minidoka | 21 | 514 | 28 | 4,877 | 2,249 | 7,689 |
| Nez Perce | 69 | 2,410 | 119 | 8,536 | 9,787 | 20,921 |
| Oneida | 7 | 86 | 16 | 1,838 | 518 | 2,465 |
| Owyhee | 26 | 344 | 27 | 3,135 | 1,316 | 4,848 |
| Payette | 36 | 834 | 56 | 6,084 | 3,582 | 10,592 |
| Power | 6 | 378 | 12 | 1,709 | 1,177 | 3,282 |
| Shoshone | 20 | 1,346 | 22 | 2,403 | 2,552 | 6,343 |
| Teton | 16 | 1,135 | 51 | 2,425 | 2,359 | 5,986 |
| Twin Falls | 137 | 2,820 | 246 | 19,623 | 11,865 | 34,691 |
| Valley | 16 | 832 | 31 | 3,125 | 2,174 | 6,178 |
| Washington | 7 | 371 | 20 | 3,531 | 1,189 | 5,118 |
| Total | 2,947 | 92,633 | 6,726 | 417,357 | 295,976 | 815,639 |