| 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 | 212,950 | 38,517 | 251,467 | 184,040 | 73.19% |
| Adams | 2,616 | 184 | 2,800 | 2,131 | 76.11% |
| Bannock | 42,056 | 7,891 | 49,947 | 36,048 | 72.17% |
| Bear Lake | 3,285 | 311 | 3,596 | 2,945 | 81.90% |
| Benewah | 5,059 | 321 | 5,380 | 4,048 | 75.24% |
| Bingham | 19,209 | 3,275 | 22,484 | 17,914 | 79.67% |
| Blaine | 12,284 | 1,537 | 13,821 | 10,352 | 74.90% |
| Boise | 4,769 | 311 | 5,080 | 3,500 | 68.90% |
| Bonner | 23,455 | 2,257 | 25,712 | 18,997 | 73.88% |
| Bonneville | 45,701 | 9,768 | 55,469 | 44,021 | 79.36% |
| Boundary | 5,841 | 539 | 6,380 | 4,686 | 73.45% |
| Butte | 1,607 | 193 | 1,800 | 1,329 | 73.83% |
| Camas | 763 | 67 | 830 | 591 | 71.20% |
| Canyon | 83,490 | 10,096 | 93,586 | 67,439 | 72.06% |
| Caribou | 3,745 | 381 | 4,126 | 3,133 | 75.93% |
| Cassia | 9,748 | 1,220 | 10,968 | 8,535 | 77.82% |
| Clark | 429 | 18 | 447 | 342 | 76.51% |
| Clearwater | 4,562 | 522 | 5,084 | 3,819 | 75.12% |
| Custer | 2,887 | 272 | 3,159 | 2,426 | 76.80% |
| Elmore | 10,213 | 1,535 | 11,748 | 8,210 | 69.88% |
| Franklin | 6,070 | 864 | 6,934 | 5,701 | 82.22% |
| Fremont | 6,731 | 797 | 7,528 | 5,908 | 78.48% |
| Gem | 9,184 | 1,201 | 10,385 | 7,656 | 73.72% |
| Gooding | 6,168 | 634 | 6,802 | 5,257 | 77.29% |
| Idaho | 10,053 | 520 | 10,573 | 8,118 | 76.78% |
| Jefferson | 12,409 | 1,708 | 14,117 | 11,563 | 81.91% |
| Jerome | 8,577 | 977 | 9,554 | 6,848 | 71.68% |
| Kootenai | 72,271 | 8,114 | 80,385 | 61,029 | 75.92% |
| Latah | 21,281 | 3,567 | 24,848 | 17,319 | 69.70% |
| Lemhi | 5,079 | 230 | 5,309 | 4,193 | 78.98% |
| Lewis | 2,013 | 180 | 2,193 | 1,668 | 76.06% |
| Lincoln | 2,077 | 292 | 2,369 | 1,732 | 73.11% |
| Madison | 14,786 | 4,520 | 19,306 | 14,642 | 75.84% |
| Minidoka | 7,860 | 1,352 | 9,212 | 7,087 | 76.93% |
| Nez Perce | 21,241 | 2,157 | 23,398 | 17,267 | 73.80% |
| Oneida | 2,499 | 284 | 2,783 | 2,182 | 78.40% |
| Owyhee | 4,853 | 529 | 5,382 | 3,776 | 70.16% |
| Payette | 10,051 | 1,627 | 11,678 | 8,638 | 73.97% |
| Power | 3,287 | 408 | 3,695 | 2,954 | 79.95% |
| Shoshone | 6,664 | 649 | 7,313 | 5,428 | 74.22% |
| Teton | 5,562 | 795 | 6,357 | 4,591 | 72.22% |
| Twin Falls | 33,356 | 6,386 | 39,742 | 28,766 | 72.38% |
| Valley | 6,161 | 619 | 6,780 | 5,010 | 73.89% |
| Washington | 5,071 | 636 | 5,707 | 4,451 | 77.99% |
| Total | 777,973 | 118,261 | 896,234 | 666,290 | 74.34% |