| County | Constitution | Democratic | Libertarian | Republican | Unaffiliated | Total Registered |
|---|---|---|---|---|---|---|
| Ada | 584 | 41,241 | 2,530 | 101,366 | 89,451 | 235,172 |
| Adams | 15 | 170 | 15 | 1,672 | 649 | 2,521 |
| Bannock | 129 | 4,432 | 374 | 17,200 | 18,102 | 40,237 |
| Bear Lake | 16 | 109 | 7 | 2,586 | 587 | 3,305 |
| Benewah | 26 | 520 | 25 | 2,430 | 2,042 | 5,043 |
| Bingham | 75 | 1,474 | 73 | 12,429 | 5,194 | 19,245 |
| Blaine | 10 | 2,672 | 106 | 3,316 | 6,570 | 12,674 |
| Boise | 22 | 325 | 35 | 2,830 | 1,353 | 4,565 |
| Bonner | 152 | 2,358 | 220 | 14,635 | 7,511 | 24,876 |
| Bonneville | 150 | 3,582 | 351 | 29,279 | 16,889 | 50,251 |
| Boundary | 24 | 419 | 49 | 4,079 | 1,527 | 6,098 |
| Butte | 5 | 58 | 5 | 1,147 | 261 | 1,476 |
| Camas | 5 | 29 | 5 | 457 | 184 | 680 |
| Canyon | 398 | 8,765 | 747 | 44,959 | 31,144 | 86,013 |
| Caribou | 19 | 101 | 10 | 2,697 | 826 | 3,653 |
| Cassia | 28 | 445 | 32 | 6,701 | 2,024 | 9,230 |
| Clark | 2 | 17 | 2 | 314 | 51 | 386 |
| Clearwater | 9 | 368 | 24 | 2,238 | 1,697 | 4,336 |
| Custer | 4 | 139 | 17 | 2,024 | 613 | 2,797 |
| Elmore | 32 | 910 | 75 | 5,843 | 3,160 | 10,020 |
| Franklin | 38 | 164 | 28 | 4,598 | 1,256 | 6,084 |
| Fremont | 29 | 268 | 19 | 5,043 | 1,288 | 6,647 |
| Gem | 44 | 580 | 53 | 6,080 | 2,579 | 9,336 |
| Gooding | 22 | 516 | 33 | 3,747 | 1,779 | 6,097 |
| Idaho | 36 | 536 | 52 | 6,576 | 2,355 | 9,555 |
| Jefferson | 41 | 394 | 48 | 9,858 | 2,810 | 13,151 |
| Jerome | 122 | 647 | 37 | 4,384 | 2,687 | 7,877 |
| Kootenai | 314 | 8,198 | 615 | 42,377 | 26,158 | 77,662 |
| Latah | 85 | 4,182 | 300 | 7,567 | 9,622 | 21,756 |
| Lemhi | 9 | 356 | 22 | 3,198 | 1,164 | 4,749 |
| Lewis | 7 | 153 | 7 | 1,244 | 606 | 2,017 |
| Lincoln | 7 | 161 | 14 | 1,332 | 593 | 2,107 |
| Madison | 84 | 515 | 163 | 12,952 | 4,395 | 18,109 |
| Minidoka | 21 | 513 | 27 | 4,893 | 2,193 | 7,647 |
| Nez Perce | 69 | 2,406 | 117 | 8,525 | 9,793 | 20,910 |
| Oneida | 7 | 93 | 15 | 1,878 | 460 | 2,453 |
| Owyhee | 26 | 343 | 27 | 3,122 | 1,313 | 4,831 |
| Payette | 36 | 855 | 56 | 6,233 | 3,498 | 10,678 |
| Power | 6 | 380 | 12 | 1,712 | 1,178 | 3,288 |
| Shoshone | 21 | 1,347 | 23 | 2,402 | 2,546 | 6,339 |
| Teton | 16 | 1,145 | 50 | 2,407 | 2,371 | 5,989 |
| Twin Falls | 135 | 2,819 | 244 | 19,621 | 11,730 | 34,549 |
| Valley | 16 | 862 | 31 | 3,292 | 2,072 | 6,273 |
| Washington | 7 | 375 | 19 | 3,528 | 1,187 | 5,116 |
| Total | 2,903 | 95,942 | 6,714 | 424,771 | 285,468 | 815,798 |