| Counties | Total Number of Registered Voters at Cutoff | Number of Election Day Registrants | Total Number of Registered Voters | Number of Ballots Cast | % of Registered Voters That Voted |
|---|---|---|---|---|---|
| Ada | 181,741 | 20,332 | 202,073 | 123,413 | 61.1% |
| Adams | 2,431 | 126 | 2,557 | 1,728 | 67.6% |
| Bannock | 40,447 | 3,625 | 44,072 | 25,598 | 58.1% |
| Bear Lake | 3,354 | 124 | 3,478 | 2,294 | 66.0% |
| Benewah | 4,849 | 121 | 4,970 | 2,929 | 58.9% |
| Bingham | 19,854 | 1,507 | 21,361 | 13,031 | 61.0% |
| Blaine | 11,328 | 372 | 11,700 | 7,434 | 63.5% |
| Boise | 4,382 | 261 | 4,643 | 2,930 | 63.1% |
| Bonner | 21,244 | 1,056 | 22,300 | 14,189 | 63.6% |
| Bonneville | 43,641 | 4,477 | 48,118 | 30,916 | 64.3% |
| Boundary | 5,644 | 305 | 5,949 | 3,239 | 54.4% |
| Butte | 1,769 | 74 | 1,843 | 1,136 | 61.6% |
| Camas | 803 | 67 | 870 | 453 | 52.1% |
| Canyon | 67,916 | 4,593 | 72,509 | 43,267 | 59.7% |
| Caribou | 4,184 | 128 | 4,312 | 2,570 | 59.6% |
| Cassia | 9,498 | 582 | 10,080 | 5,843 | 58.0% |
| Clark | 400 | 11 | 411 | 347 | 84.4% |
| Clearwater | 4,863 | 197 | 5,060 | 3,073 | 60.7% |
| Custer | 2,701 | 151 | 2,852 | 1,940 | 68.0% |
| Elmore | 9,422 | 632 | 10,054 | 5,717 | 56.9% |
| Franklin | 5,939 | 260 | 6,199 | 4,061 | 65.5% |
| Fremont | 6,543 | 463 | 7,006 | 4,470 | 63.8% |
| Gem | 8,570 | 806 | 9,376 | 5,785 | 61.7% |
| Gooding | 6,383 | 307 | 6,690 | 4,231 | 63.2% |
| Idaho | 9,503 | 412 | 9,915 | 6,510 | 65.7% |
| Jefferson | 10,441 | 825 | 11,266 | 7,473 | 66.3% |
| Jerome | 8,144 | 384 | 8,528 | 4,996 | 58.6% |
| Kootenai | 64,803 | 3,390 | 68,193 | 37,973 | 55.7% |
| Latah | 21,233 | 1,902 | 23,135 | 12,309 | 53.2% |
| Lemhi | 5,104 | 110 | 5,214 | 3,244 | 62.2% |
| Lewis | 2,055 | 104 | 2,159 | 1,416 | 65.6% |
| Lincoln | 2,176 | 109 | 2,285 | 1,444 | 63.2% |
| Madison | 13,326 | 1,452 | 14,778 | 8,143 | 55.1% |
| Minidoka | 8,414 | 309 | 8,723 | 5,225 | 59.9% |
| Nez Perce | 20,967 | 1,041 | 22,008 | 12,453 | 56.6% |
| Oneida | 2,400 | 100 | 2,500 | 1,595 | 63.8% |
| Owyhee | 4,176 | 552 | 4,728 | 2,939 | 62.2% |
| Payette | 9,616 | 735 | 10,351 | 5,915 | 57.1% |
| Power | 3,409 | 142 | 3,551 | 2,214 | 62.3% |
| Shoshone | 6,790 | 192 | 6,982 | 3,854 | 55.2% |
| Teton | 4,469 | 320 | 4,789 | 3,100 | 64.7% |
| Twin Falls | 34,569 | 1,187 | 35,756 | 20,095 | 56.2% |
| Valley | 5,940 | 308 | 6,248 | 3,970 | 63.5% |
| Washington | 4,908 | 380 | 5,288 | 3,465 | 65.5% |
| TOTAL | 710,349 | 54,531 | 764,880 | 458,927 | 60.0% |