| Counties | Total Number of Registered Voters at Cutoff | Number Election Day Registrants | Total Number Registered Voters | Number Ballots Cast | % of Registered Voters That Voted |
|---|---|---|---|---|---|
| Ada | 194,758 | 38,279 | 233,037 | 181,656 | 77.95% |
| Adams | 2,703 | 239 | 2,942 | 2,387 | 81.14% |
| Bannock | 40,110 | 8,204 | 48,314 | 35,627 | 73.74% |
| Bear Lake | 3,463 | 395 | 3,858 | 3,112 | 80.66% |
| Benewah | 5,059 | 367 | 5,426 | 4,305 | 79.34% |
| Bingham | 19,671 | 3,639 | 23,310 | 17,519 | 75.16% |
| Blaine | 12,416 | 1,572 | 13,988 | 10,707 | 76.54% |
| Boise | 4,704 | 441 | 5,145 | 3,840 | 74.64% |
| Bonner | 23,569 | 2,253 | 25,822 | 20,042 | 77.62% |
| Bonneville | 45,501 | 9,683 | 55,184 | 42,376 | 76.79% |
| Boundary | 6,008 | 438 | 6,446 | 4,847 | 75.19% |
| Butte | 1,716 | 155 | 1,871 | 1,446 | 77.28% |
| Camas | 762 | 75 | 837 | 628 | 75.03% |
| Canyon | 72,650 | 9,672 | 82,322 | 65,359 | 79.39% |
| Caribou | 4,150 | 312 | 4,462 | 3,404 | 76.29% |
| Cassia | 9,001 | 1,384 | 10,385 | 7,979 | 76.83% |
| Clark | 417 | 31 | 448 | 390 | 87.05% |
| Clearwater | 4,686 | 415 | 5,101 | 4,012 | 78.65% |
| Custer | 2,745 | 239 | 2,984 | 2,419 | 81.07% |
| Elmore | 10,180 | 1,701 | 11,881 | 8,583 | 72.24% |
| Franklin | 6,145 | 608 | 6,753 | 5,245 | 77.67% |
| Fremont | 6,766 | 787 | 7,553 | 6,015 | 79.64% |
| Gem | 9,107 | 987 | 10,094 | 8,118 | 80.42% |
| Gooding | 6,039 | 779 | 6,818 | 5,537 | 81.21% |
| Idaho | 10,197 | 617 | 10,814 | 8,519 | 78.78% |
| Jefferson | 11,333 | 1,540 | 12,873 | 10,630 | 82.58% |
| Jerome | 9,145 | 953 | 10,098 | 7,055 | 69.87% |
| Kootenai | 70,426 | 8,802 | 79,228 | 63,034 | 79.56% |
| Latah | 22,660 | 3,513 | 26,173 | 18,071 | 69.04% |
| Lemhi | 5,040 | 372 | 5,412 | 4,186 | 77.35% |
| Lewis | 2,098 | 215 | 2,313 | 1,856 | 80.24% |
| Lincoln | 2,163 | 308 | 2,471 | 1,899 | 76.85% |
| Madison | 14,334 | 4,130 | 18,464 | 13,330 | 72.19% |
| Minidoka | 8,456 | 953 | 9,409 | 7,118 | 75.65% |
| Nez Perce | 21,957 | 2,325 | 24,282 | 18,344 | 75.55% |
| Oneida | 2,632 | 209 | 2,841 | 2,217 | 78.04% |
| Owyhee | 4,550 | 730 | 5,280 | 4,187 | 79.30% |
| Payette | 9,792 | 1,542 | 11,334 | 8,775 | 77.42% |
| Power | 3,357 | 357 | 3,714 | 2,900 | 78.08% |
| Shoshone | 6,364 | 802 | 7,166 | 5,908 | 82.44% |
| Teton | 5,380 | 695 | 6,075 | 4,717 | 77.65% |
| Twin Falls | 33,215 | 4,465 | 37,680 | 29,225 | 77.56% |
| Valley | 6,354 | 695 | 7,049 | 5,360 | 76.04% |
| Washington | 5,104 | 777 | 5,881 | 4,615 | 78.47% |
| TOTAL | 746,883 | 116,655 | 863,538 | 667,499 | 77.30% |