| County | Election Day Registrants | Total Registered Voters | Ballots Cast | Percentage |
|---|---|---|---|---|
| Ada | 2,609 | 148,416 | 33,273 | 22.4 % |
| Adams | 31 | 2,532 | 1,175 | 46.4 % |
| Bannock | 191 | 41,214 | 6,739 | 16.4 % |
| Bear Lake | 54 | 3,650 | 1,206 | 33.0 % |
| Benewah | 48 | 4,640 | 1,477 | 31.8 % |
| Bingham | 633 | 19,266 | 6,825 | 35.4 % |
| Blaine | 74 | 10,227 | 1,778 | 17.4 % |
| Boise | 54 | 4,328 | 1,203 | 27.8 % |
| Bonner | 419 | 18,247 | 6,212 | 34.0 % |
| Bonneville | 697 | 40,591 | 11,964 | 29.5 % |
| Boundary | 25 | 5,123 | 1,100 | 21.5 % |
| Butte | 14 | 1,963 | 720 | 36.7 % |
| Camas | 13 | 638 | 371 | 58.2 % |
| Canyon | 540 | 51,677 | 13,821 | 26.7 % |
| Caribou | 63 | 4,153 | 1,060 | 25.5 % |
| Cassia | 205 | 9,584 | 3,781 | 39.5 % |
| Clark | 12 | 593 | 338 | 57.0 % |
| Clearwater | 15 | 4,896 | 963 | 19.7 % |
| Custer | 43 | 2,842 | 993 | 34.9 % |
| Elmore | 241 | 9,219 | 3,487 | 37.8 % |
| Franklin | 143 | 5,357 | 2,123 | 39.6 % |
| Fremont | 143 | 6,192 | 2,686 | 43.4 % |
| Gem | 212 | 7,899 | 3,026 | 38.3 % |
| Gooding | 74 | 6,864 | 2,021 | 29.4 % |
| Idaho | 158 | 9,569 | 3,938 | 41.2 % |
| Jefferson | 218 | 9,135 | 3,323 | 36.4 % |
| Jerome | 75 | 8,356 | 2,667 | 31.9 % |
| Kootenai | 122 | 52,195 | 8,371 | 16.0 % |
| Latah | 543 | 20,554 | 5,393 | 26.2 % |
| Lemhi | 100 | 4,503 | 2,025 | 45.0 % |
| Lewis | 20 | 2,288 | 681 | 29.8 % |
| Lincoln | 65 | 2,135 | 816 | 38.2 % |
| Madison | 293 | 10,248 | 4,139 | 40.4 % |
| Minidoka | 94 | 8,905 | 3,285 | 36.9 % |
| Nez Perce | 159 | 20,784 | 4,637 | 22.3 % |
| Oneida | 27 | 2,222 | 568 | 25.6 % |
| Owyhee | 109 | 4,463 | 1,651 | 37.0 % |
| Payette | 249 | 9,068 | 3,141 | 34.6 % |
| Power | 29 | 3,661 | 953 | 26.0 % |
| Shoshone | 122 | 7,751 | 2,316 | 29.9 % |
| Teton | 45 | 3,199 | 1,189 | 37.2 % |
| Twin Falls | 271 | 29,343 | 7,906 | 26.9 % |
| Valley | 227 | 5,694 | 2,304 | 40.5 % |
| Washington | 80 | 5,294 | 2,634 | 49.8 % |
| Total | 9,559 | 629,478 | 170,279 | 27.1 % |
| 1st Cong. Dist. | 4,901 | 334,099 | 86,358 | 25.8 % |
| 2nd Cong. Dist. | 4,658 | 292,770 | 83,920 | 28.7 % |