Voter Registration Totals as of April 2, 2018
| County |
Constitution |
Democratic |
Libertarian |
Republican |
Unaffiliated |
Total Registered |
| Ada |
593 |
36,645 |
2,479 |
92,375 |
98,497 |
230,589 |
| Adams |
15 |
161 |
14 |
1,623 |
647 |
2,460 |
| Bannock |
133 |
4,312 |
362 |
16,364 |
18,686 |
39,857 |
| Bear Lake |
15 |
96 |
6 |
2,537 |
600 |
3,254 |
| Benewah |
29 |
508 |
26 |
2,252 |
2,163 |
4,978 |
| Bingham |
79 |
1,359 |
71 |
11,691 |
5,779 |
18,979 |
| Blaine |
9 |
2,571 |
100 |
3,110 |
6,737 |
12,527 |
| Boise |
23 |
301 |
34 |
2,627 |
1,486 |
4,471 |
| Bonner |
155 |
2,235 |
208 |
13,259 |
8,540 |
24,397 |
| Bonneville |
156 |
3,425 |
358 |
28,232 |
18,357 |
50,528 |
| Boundary |
24 |
393 |
49 |
3,850 |
1,661 |
5,977 |
| Butte |
5 |
57 |
3 |
1,038 |
330 |
1,433 |
| Camas |
5 |
27 |
4 |
447 |
180 |
663 |
| Canyon |
407 |
8,328 |
734 |
43,678 |
31,119 |
84,266 |
| Caribou |
19 |
93 |
10 |
2,665 |
832 |
3,619 |
| Cassia |
28 |
432 |
32 |
6,630 |
2,068 |
9,190 |
| Clark |
2 |
17 |
2 |
291 |
51 |
363 |
| Clearwater |
9 |
356 |
23 |
2,112 |
1,800 |
4,300 |
| Custer |
4 |
133 |
15 |
1,893 |
691 |
2,736 |
| Elmore |
33 |
890 |
70 |
5,556 |
3,340 |
9,889 |
| Franklin |
40 |
157 |
27 |
4,540 |
1,314 |
6,078 |
| Fremont |
31 |
256 |
19 |
4,750 |
1,446 |
6,502 |
| Gem |
45 |
552 |
50 |
5,740 |
2,866 |
9,253 |
| Gooding |
21 |
488 |
31 |
3,455 |
2,029 |
6,024 |
| Idaho |
37 |
519 |
51 |
6,440 |
2,444 |
9,491 |
| Jefferson |
44 |
371 |
49 |
9,342 |
3,082 |
12,888 |
| Jerome |
127 |
581 |
36 |
4,154 |
2,865 |
7,763 |
| Kootenai |
315 |
7,440 |
582 |
39,830 |
28,065 |
76,232 |
| Latah |
83 |
4,110 |
296 |
6,886 |
10,321 |
21,696 |
| Lemhi |
10 |
327 |
23 |
3,130 |
1,244 |
4,734 |
| Lewis |
9 |
137 |
7 |
1,155 |
683 |
1,991 |
| Lincoln |
7 |
164 |
14 |
1,279 |
634 |
2,098 |
| Madison |
84 |
503 |
164 |
12,556 |
4,670 |
17,977 |
| Minidoka |
21 |
507 |
29 |
4,737 |
2,351 |
7,645 |
| Nez Perce |
64 |
2,354 |
119 |
8,001 |
10,228 |
20,766 |
| Oneida |
8 |
85 |
16 |
1,778 |
542 |
2,429 |
| Owyhee |
28 |
322 |
28 |
2,965 |
1,423 |
4,766 |
| Payette |
34 |
810 |
56 |
5,998 |
3,604 |
10,502 |
| Power |
6 |
374 |
12 |
1,601 |
1,240 |
3,233 |
| Shoshone |
20 |
1,337 |
22 |
2,258 |
2,646 |
6,283 |
| Teton |
15 |
1,107 |
56 |
2,360 |
2,422 |
5,960 |
| Twin Falls |
136 |
2,709 |
233 |
18,580 |
12,485 |
34,143 |
| Valley |
17 |
804 |
31 |
3,012 |
2,252 |
6,116 |
| Washington |
7 |
352 |
20 |
3,372 |
1,282 |
5,033 |
| Total |
2,952 |
88,705 |
6,571 |
400,149 |
305,702 |
804,079 |