| County | Total Registered Voters | Ballots Cast | Percentage |
|---|---|---|---|
| Ada | 129,019 | 42,464 | 32.9 % |
| Adams | 2,275 | 1,123 | 49.4 % |
| Bannock | 36,265 | 12,481 | 34.4 % |
| Bear Lake | 3,545 | 2,314 | 65.3 % |
| Benewah | 4,399 | 1,005 | 22.8 % |
| Bingham | 18,970 | 6,540 | 34.5 % |
| Blaine | 9,361 | 1,549 | 16.5 % |
| Boise | 3,174 | 1,707 | 53.8 % |
| Bonner | 16,345 | 5,451 | 33.3 % |
| Bonneville | 40,134 | 12,664 | 31.6 % |
| Boundary | 4,657 | 2,020 | 43.4 % |
| Butte | 1,733 | 687 | 39.6 % |
| Camas | 574 | 435 | 75.8 % |
| Canyon | 44,424 | 14,784 | 33.3 % |
| Caribou | 3,699 | 1,461 | 39.5 % |
| Cassia | 8,789 | 3,253 | 37.0 % |
| Clark | 496 | 232 | 46.8 % |
| Clearwater | 4,793 | 1,251 | 26.1 % |
| Custer | 2,517 | 734 | 29.2 % |
| Elmore | 8,318 | 2,574 | 30.9 % |
| Franklin | 5,292 | 2,443 | 46.2 % |
| Fremont | 5,604 | 2,791 | 49.8 % |
| Gem | 6,780 | 2,770 | 40.9 % |
| Gooding | 6,357 | 2,457 | 38.7 % |
| Idaho | 8,107 | 3,429 | 42.3 % |
| Jefferson | 8,403 | 3,070 | 36.5 % |
| Jerome | 7,887 | 2,503 | 31.7 % |
| Kootenai | 44,941 | 9,821 | 21.9 % |
| Latah | 19,881 | 7,943 | 40.0 % |
| Lemhi | 4,418 | 1,790 | 40.5 % |
| Lewis | 2,146 | 788 | 36.7 % |
| Lincoln | 1,981 | 1,077 | 54.4 % |
| Madison | 9,492 | 3,835 | 40.4 % |
| Minidoka | 8,521 | 3,069 | 36.0 % |
| Nez Perce | 20,145 | 5,193 | 25.8 % |
| Oneida | 2,128 | 880 | 41.4 % |
| Owyhee | 3,779 | 1,604 | 42.4 % |
| Payette | 8,416 | 2,438 | 29.0 % |
| Power | 3,665 | 1,023 | 27.9 % |
| Shoshone | 8,239 | 3,707 | 45.0 % |
| Teton | 2,317 | 769 | 33.2 % |
| Twin Falls | 31,549 | 8,458 | 26.8 % |
| Valley | 4,999 | 1,888 | 37.8 % |
| Washington | 5,044 | 2,498 | 49.5 % |
| Total | 573,578 | 190,973 | 33.3 % |
| 1st Cong. Dist. | 296,908 | 97,462 | 32.8 % |
| 2nd Cong. Dist. | 276,670 | 93,511 | 33.8 % |