| 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 | 198,302 | 3,011 | 201,313 | 43,958 | 21.8% |
| Adams | 2,657 | 48 | 2,705 | 1,145 | 42.3% |
| Bannock | 39,581 | 436 | 40,017 | 9,096 | 22.7% |
| Bear Lake | 3,253 | 104 | 3,357 | 1,794 | 53.4% |
| Benewah | 4,902 | 47 | 4,949 | 1,575 | 31.8% |
| Bingham | 19,506 | 495 | 20,001 | 6,978 | 34.9% |
| Blaine | 11,879 | 193 | 12,072 | 3,619 | 30.0% |
| Boise | 4,431 | 166 | 4,597 | 1,765 | 38.4% |
| Bonner | 22,699 | 279 | 22,978 | 6,553 | 28.5% |
| Bonneville | 44,547 | 557 | 45,104 | 12,424 | 27.5% |
| Boundary | 5,632 | 53 | 5,685 | 1,691 | 29.7% |
| Butte | 1,638 | 26 | 1,664 | 571 | 34.3% |
| Camas | 749 | 27 | 776 | 434 | 55.9% |
| Canyon | 73,338 | 515 | 73,853 | 17,383 | 23.5% |
| Caribou | 3,859 | 51 | 3,910 | 1,450 | 37.1% |
| Cassia | 8,740 | 335 | 9,075 | 4,272 | 47.1% |
| Clark | 405 | 20 | 425 | 341 | 80.2% |
| Clearwater | 4,395 | 111 | 4,506 | 1,543 | 34.2% |
| Custer | 2,753 | 49 | 2,802 | 1,209 | 43.1% |
| Elmore | 9,573 | 233 | 9,806 | 3,265 | 33.3% |
| Franklin | 6,015 | 63 | 6,078 | 2,404 | 39.6% |
| Fremont | 6,657 | 123 | 6,780 | 3,076 | 45.4% |
| Gem | 8,994 | 153 | 9,147 | 3,014 | 33.0% |
| Gooding | 6,230 | 56 | 6,286 | 1,895 | 30.1% |
| Idaho | 9,628 | 200 | 9,828 | 3,907 | 39.8% |
| Jefferson | 11,870 | 175 | 12,045 | 3,972 | 33.0% |
| Jerome | 8,139 | 96 | 8,235 | 2,545 | 30.9% |
| Kootenai | 69,633 | 709 | 70,342 | 15,564 | 22.1% |
| Latah | 20,742 | 295 | 21,037 | 5,202 | 24.7% |
| Lemhi | 4,916 | 112 | 5,028 | 2,011 | 40.0% |
| Lewis | 2,025 | 15 | 2,040 | 960 | 47.1% |
| Lincoln | 2,080 | 102 | 2,182 | 907 | 41.6% |
| Madison | 15,083 | 442 | 15,525 | 4,935 | 31.8% |
| Minidoka | 7,864 | 52 | 7,916 | 2,893 | 36.5% |
| Nez Perce | 20,439 | 118 | 20,557 | 4,126 | 20.1% |
| Oneida | 2,450 | 58 | 2,508 | 993 | 39.6% |
| Owyhee | 4,594 | 67 | 4,661 | 1,827 | 39.2% |
| Payette | 9,966 | 87 | 10,053 | 2,358 | 23.5% |
| Power | 3,207 | 46 | 3,253 | 1,270 | 39.0% |
| Shoshone | 6,558 | 84 | 6,642 | 2,329 | 35.1% |
| Teton | 5,312 | 161 | 5,473 | 2,294 | 41.9% |
| Twin Falls | 32,979 | 247 | 33,226 | 8,835 | 26.6% |
| Valley | 6,161 | 161 | 6,322 | 2,271 | 35.9% |
| Washington | 5,006 | 135 | 5,141 | 2,361 | 45.9% |
| TOTAL | 739,387 | 10,513 | 749,900 | 203,015 | 27.1% |