| County | Constitution | Democratic | Libertarian | Republican | Unaffiliated | Total Registered |
|---|---|---|---|---|---|---|
| Ada | 603 | 37,315 | 2,537 | 93,650 | 98,368 | 232,473 |
| Adams | 15 | 170 | 15 | 1,649 | 649 | 2,498 |
| Bannock | 137 | 4,391 | 374 | 16,521 | 18,889 | 40,312 |
| Bear Lake | 17 | 107 | 7 | 2,549 | 608 | 3,288 |
| Benewah | 30 | 516 | 27 | 2,272 | 2,154 | 4,999 |
| Bingham | 79 | 1,372 | 73 | 11,721 | 5,787 | 19,032 |
| Blaine | 9 | 2,594 | 100 | 3,132 | 6,757 | 12,592 |
| Boise | 23 | 306 | 36 | 2,659 | 1,491 | 4,515 |
| Bonner | 157 | 2,282 | 214 | 13,453 | 8,509 | 24,615 |
| Bonneville | 156 | 3,478 | 368 | 28,343 | 18,473 | 50,818 |
| Boundary | 24 | 406 | 49 | 3,911 | 1,647 | 6,037 |
| Butte | 5 | 56 | 4 | 1,043 | 328 | 1,436 |
| Camas | 5 | 26 | 4 | 451 | 181 | 667 |
| Canyon | 411 | 8,478 | 752 | 44,096 | 31,225 | 84,962 |
| Caribou | 20 | 94 | 10 | 2,668 | 833 | 3,625 |
| Cassia | 30 | 433 | 32 | 6,634 | 2,064 | 9,193 |
| Clark | 2 | 17 | 2 | 289 | 52 | 362 |
| Clearwater | 9 | 368 | 24 | 2,133 | 1,788 | 4,322 |
| Custer | 4 | 136 | 15 | 1,901 | 690 | 2,746 |
| Elmore | 33 | 903 | 73 | 5,602 | 3,337 | 9,948 |
| Franklin | 40 | 157 | 28 | 4,546 | 1,323 | 6,094 |
| Fremont | 31 | 258 | 19 | 4,793 | 1,443 | 6,544 |
| Gem | 46 | 559 | 53 | 5,794 | 2,844 | 9,296 |
| Gooding | 21 | 491 | 32 | 3,471 | 2,020 | 6,035 |
| Idaho | 38 | 524 | 55 | 6,461 | 2,435 | 9,513 |
| Jefferson | 44 | 376 | 49 | 9,393 | 3,100 | 12,962 |
| Jerome | 127 | 590 | 38 | 4,179 | 2,877 | 7,811 |
| Kootenai | 320 | 7,661 | 604 | 40,298 | 28,046 | 76,929 |
| Latah | 85 | 4,147 | 297 | 6,956 | 10,317 | 21,802 |
| Lemhi | 10 | 328 | 23 | 3,129 | 1,243 | 4,733 |
| Lewis | 9 | 137 | 7 | 1,165 | 681 | 1,999 |
| Lincoln | 7 | 163 | 14 | 1,276 | 631 | 2,091 |
| Madison | 86 | 506 | 165 | 12,628 | 4,677 | 18,062 |
| Minidoka | 21 | 509 | 30 | 4,755 | 2,350 | 7,665 |
| Nez Perce | 70 | 2,380 | 121 | 8,051 | 10,228 | 20,850 |
| Oneida | 9 | 85 | 16 | 1,791 | 546 | 2,447 |
| Owyhee | 29 | 320 | 30 | 2,983 | 1,418 | 4,780 |
| Payette | 37 | 820 | 56 | 6,046 | 3,601 | 10,560 |
| Power | 6 | 374 | 12 | 1,604 | 1,247 | 3,243 |
| Shoshone | 20 | 1,334 | 22 | 2,265 | 2,662 | 6,303 |
| Teton | 16 | 1,126 | 55 | 2,356 | 2,413 | 5,966 |
| Twin Falls | 139 | 2,755 | 240 | 18,712 | 12,511 | 34,357 |
| Valley | 18 | 827 | 31 | 3,053 | 2,247 | 6,176 |
| Washington | 8 | 355 | 20 | 3,389 | 1,290 | 5,062 |
| Total | 3,006 | 90,230 | 6,733 | 403,771 | 305,980 | 809,720 |