| County | Election Day Registrants | Total Registered Voters | Ballots Cast | Percentage |
|---|---|---|---|---|
| Ada | 1,942 | 141,866 | 32,758 | 23.1 % |
| Adams | 89 | 2,486 | 1,592 | 64.0 % |
| Bannock | 198 | 39,458 | 7,904 | 20.0 % |
| Bear Lake | 140 | 3,838 | 2,479 | 64.6 % |
| Benewah | 103 | 4,582 | 1,784 | 38.9 % |
| Bingham | 772 | 19,441 | 7,553 | 38.9 % |
| Blaine | 280 | 9,750 | 4,377 | 44.9 % |
| Boise | 104 | 3,890 | 1,656 | 42.6 % |
| Bonner | 329 | 18,020 | 6,638 | 36.8 % |
| Bonneville | 678 | 41,455 | 11,711 | 28.2 % |
| Boundary | 36 | 5,021 | 1,503 | 29.9 % |
| Butte | 49 | 1,853 | 956 | 51.6 % |
| Camas | 51 | 694 | 541 | 78.0 % |
| Canyon | 375 | 48,623 | 11,590 | 23.8 % |
| Caribou | 29 | 3,826 | 905 | 23.7 % |
| Cassia | 165 | 9,584 | 3,508 | 36.6 % |
| Clark | 10 | 572 | 333 | 58.2 % |
| Clearwater | 56 | 4,934 | 1,662 | 33.7 % |
| Custer | 191 | 2,973 | 1,529 | 51.4 % |
| Elmore | 109 | 9,187 | 2,570 | 28.0 % |
| Franklin | 30 | 5,151 | 759 | 14.7 % |
| Fremont | 140 | 6,363 | 2,682 | 42.1 % |
| Gem | 168 | 7,455 | 2,796 | 37.5 % |
| Gooding | 141 | 7,016 | 2,969 | 42.3 % |
| Idaho | 170 | 8,936 | 4,030 | 45.1 % |
| Jefferson | 104 | 8,820 | 2,326 | 26.4 % |
| Jerome | 41 | 8,262 | 3,052 | 36.9 % |
| Kootenai | 315 | 51,733 | 9,455 | 18.3 % |
| Latah | 222 | 21,246 | 4,865 | 22.9 % |
| Lemhi | 76 | 4,687 | 2,041 | 43.5 % |
| Lewis | 24 | 2,296 | 742 | 32.3 % |
| Lincoln | 28 | 2,167 | 913 | 42.1 % |
| Madison | 240 | 9,440 | 3,822 | 40.5 % |
| Minidoka | 78 | 8,972 | 2,984 | 33.3 % |
| Nez Perce | 267 | 21,090 | 6,285 | 29.8 % |
| Oneida | 16 | 2,314 | 385 | 16.6 % |
| Owyhee | 198 | 4,378 | 2,111 | 48.2 % |
| Payette | 96 | 8,976 | 1,749 | 19.5 % |
| Power | 16 | 3,706 | 847 | 22.9 % |
| Shoshone | 240 | 8,349 | 4,025 | 48.2 % |
| Teton | 18 | 3,077 | 1,327 | 43.1 % |
| Twin Falls | 199 | 31,088 | 4,448 | 14.3 % |
| Valley | 203 | 5,416 | 2,651 | 48.9 % |
| Washington | 62 | 5,171 | 2,105 | 40.7 % |
| Total | 8,798 | 618,162 | 172,918 | 28.0 % |
| 1st Cong. Dist. | 4,355 | 327,141 | 88,634 | 27.1 % |
| 2nd Cong. Dist. | 4,443 | 291,021 | 84,284 | 29.0 % |