| County | Constitution | Democratic | Libertarian | Republican | Unaffiliated | Total Registered |
|---|---|---|---|---|---|---|
| Ada | 594 | 39,186 | 2,540 | 97,431 | 95,194 | 234,944 |
| Adams | 15 | 171 | 15 | 1,675 | 645 | 2,521 |
| Bannock | 128 | 4,436 | 374 | 17,227 | 18,110 | 40,275 |
| Bear Lake | 16 | 109 | 7 | 2,587 | 588 | 3,307 |
| Benewah | 28 | 525 | 27 | 2,415 | 2,043 | 5,038 |
| Bingham | 77 | 1,469 | 73 | 12,376 | 5,249 | 19,244 |
| Blaine | 10 | 2,663 | 105 | 3,332 | 6,569 | 12,679 |
| Boise | 22 | 324 | 35 | 2,829 | 1,350 | 4,560 |
| Bonner | 153 | 2,329 | 218 | 14,127 | 7,854 | 24,682 |
| Bonneville | 149 | 3,578 | 353 | 29,396 | 16,969 | 50,445 |
| Boundary | 24 | 419 | 49 | 4,072 | 1,530 | 6,094 |
| Butte | 5 | 58 | 5 | 1,149 | 261 | 1,478 |
| Camas | 5 | 29 | 5 | 457 | 186 | 682 |
| Canyon | 402 | 8,736 | 747 | 45,003 | 31,069 | 85,957 |
| Caribou | 19 | 101 | 10 | 2,697 | 824 | 3,651 |
| Cassia | 28 | 450 | 32 | 6,724 | 2,028 | 9,262 |
| Clark | 2 | 17 | 2 | 314 | 51 | 386 |
| Clearwater | 9 | 368 | 24 | 2,249 | 1,703 | 4,353 |
| Custer | 4 | 139 | 17 | 2,025 | 613 | 2,798 |
| Elmore | 32 | 912 | 74 | 5,840 | 3,161 | 10,019 |
| Franklin | 37 | 164 | 28 | 4,602 | 1,256 | 6,087 |
| Fremont | 27 | 268 | 19 | 5,050 | 1,290 | 6,654 |
| Gem | 45 | 576 | 53 | 6,087 | 2,580 | 9,341 |
| Gooding | 22 | 517 | 33 | 3,757 | 1,784 | 6,113 |
| Idaho | 36 | 535 | 53 | 6,591 | 2,353 | 9,568 |
| Jefferson | 41 | 393 | 48 | 9,867 | 2,798 | 13,147 |
| Jerome | 123 | 648 | 37 | 4,417 | 2,699 | 7,924 |
| Kootenai | 312 | 8,151 | 610 | 42,354 | 26,079 | 77,506 |
| Latah | 84 | 4,171 | 298 | 7,584 | 9,604 | 21,741 |
| Lemhi | 10 | 355 | 22 | 3,202 | 1,160 | 4,749 |
| Lewis | 9 | 137 | 7 | 1,162 | 680 | 1,995 |
| Lincoln | 7 | 161 | 14 | 1,335 | 588 | 2,105 |
| Madison | 84 | 514 | 163 | 12,960 | 4,389 | 18,110 |
| Minidoka | 21 | 513 | 27 | 4,905 | 2,199 | 7,665 |
| Nez Perce | 68 | 2,403 | 118 | 8,519 | 9,788 | 20,896 |
| Oneida | 7 | 92 | 15 | 1,882 | 461 | 2,457 |
| Owyhee | 26 | 343 | 27 | 3,126 | 1,313 | 4,835 |
| Payette | 37 | 849 | 57 | 6,126 | 3,593 | 10,662 |
| Power | 6 | 378 | 12 | 1,709 | 1,177 | 3,282 |
| Shoshone | 20 | 1,344 | 22 | 2,400 | 2,541 | 6,327 |
| Teton | 16 | 1,136 | 51 | 2,413 | 2,357 | 5,973 |
| Twin Falls | 137 | 2,817 | 248 | 19,683 | 11,737 | 34,621 |
| Valley | 16 | 853 | 31 | 3,272 | 2,068 | 6,240 |
| Washington | 7 | 373 | 19 | 3,528 | 1,186 | 5,113 |
| Total | 2,920 | 93,710 | 6,724 | 420,456 | 291,677 | 815,486 |