| County | Election Day Registrants | Total Registered Voters | Ballots Cast | Percentage |
|---|---|---|---|---|
| Ada | 15,107 | 215,357 | 122,175 | 56.7% |
| Adams | 54 | 2,695 | 1,714 | 63.6% |
| Bannock | 2,927 | 42,783 | 23,942 | 56.0% |
| Bear Lake | 100 | 3,365 | 2,277 | 67.7% |
| Benewah | 95 | 5,120 | 3,079 | 60.1% |
| Bingham | 1,001 | 20,792 | 12,034 | 57.9% |
| Blaine | 453 | 12,431 | 6,694 | 53.8% |
| Boise | 223 | 4,717 | 2,800 | 59.4% |
| Bonner | 937 | 23,970 | 14,233 | 59.4% |
| Bonneville | 3,006 | 47,802 | 29,698 | 62.1% |
| Boundary | 208 | 5,962 | 3,620 | 60.7% |
| Butte | 56 | 1,687 | 1,164 | 69.0% |
| Camas | 20 | 788 | 461 | 58.5% |
| Canyon | 2,919 | 78,428 | 45,030 | 57.4% |
| Caribou | 93 | 3,920 | 2,293 | 58.5% |
| Cassia | 387 | 9,387 | 5,667 | 60.4% |
| Clark | 20 | 425 | 349 | 82.1% |
| Clearwater | 328 | 4,855 | 2,993 | 61.6% |
| Custer | 134 | 2,905 | 1,870 | 64.4% |
| Elmore | 371 | 10,550 | 5,468 | 51.8% |
| Franklin | 145 | 6,142 | 3,824 | 62.3% |
| Fremont | 236 | 7,029 | 4,068 | 57.9% |
| Gem | 420 | 9,447 | 5,562 | 58.9% |
| Gooding | 202 | 6,508 | 4,007 | 61.6% |
| Idaho | 345 | 10,249 | 6,760 | 66.0% |
| Jefferson | 545 | 12,439 | 7,570 | 60.9% |
| Jerome | 313 | 8,558 | 4,742 | 55.4% |
| Kootenai | 3,397 | 73,521 | 42,719 | 58.1% |
| Latah | 1,570 | 22,712 | 12,559 | 55.3% |
| Lemhi | 208 | 5,258 | 3,429 | 65.2% |
| Lewis | 76 | 2,095 | 1,329 | 63.4% |
| Lincoln | 75 | 2,180 | 1,253 | 57.5% |
| Madison | 1,186 | 16,227 | 7,810 | 48.1% |
| Minidoka | 371 | 8,316 | 4,909 | 59.0% |
| Nez Perce | 905 | 21,656 | 12,770 | 59.0% |
| Oneida | 127 | 2,633 | 1,656 | 62.9% |
| Owyhee | 201 | 4,879 | 2,932 | 60.1% |
| Payette | 487 | 10,548 | 6,085 | 57.7% |
| Power | 157 | 3,469 | 2,246 | 64.7% |
| Shoshone | 186 | 6,770 | 3,988 | 58.9% |
| Teton | 341 | 5,752 | 3,437 | 59.8% |
| Twin Falls | 1,090 | 34,438 | 19,042 | 55.3% |
| Valley | 311 | 6,585 | 3,921 | 59.5% |
| Washington | 276 | 5,326 | 3,569 | 67.0% |
| Total | 41,609 | 790,676 | 457,748 | 57.9% |
| 1st Cong. Dist. | 22,078 | 432,995 | 252,910 | 58.4% |
| 2nd Cong. Dist. | 19,531 | 357,681 | 204,838 | 57.3% |