| Region 7 | ||||||||
| Number of Registered Voters | ||||||||
| Source: Office of the Secretary of State | ||||||||
| 1994 | 1996 | 1998 | 2000 | 2002 | 2004 | 2006 | 2008 | |
| Bonneville | 42,413 | 46,737 | 42,714 | 47,050 | 43,255 | 50,272 | 48,118 | 55,184 |
| Butte | 1,813 | 2,007 | 1,984 | 2,166 | 2,021 | 1,991 | 1,843 | 837 |
| Clark | 539 | 614 | 615 | 509 | 427 | 432 | 411 | 448 |
| Custer | 2,734 | 3,212 | 2,967 | 3,333 | 2,855 | 3,096 | 2,852 | 2,984 |
| Fremont | 6,126 | 6,897 | 6,450 | 7,052 | 6,466 | 7,471 | 7,006 | 7,553 |
| Jefferson | 9,413 | 9,863 | 9,523 | 10,017 | 9,775 | 11,317 | 11,266 | 12,873 |
| Lemhi | 4,693 | 4,922 | 4,849 | 4,987 | 4,835 | 5,105 | 5,214 | 5,412 |
| Madison | 10,214 | 11,392 | 10,851 | 13,406 | 12,230 | 16,081 | 14,778 | 18,464 |
| Teton | 2,636 | 3,515 | 3,319 | 3,858 | 3,890 | 4,446 | 4,789 | 6,075 |
| * Population 18 years and over | ||||||||
| * This data is for the general elections of the reported years. | ||||||||