| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | D | 34,938 | 32,695 | 69,897 | |
| 2020 | D | 37,044 | 31,696 | 70,979 | |
| 2016 | D | 24,246 | 23,802 | 53,819 | |
| 2012 | R | 21,961 | 24,358 | 47,908 | |
| 2008 | D | 24,205 | 22,578 | 48,155 | |
| 2004 | R | 16,405 | 22,392 | 39,842 | |
| 2000 | R | 10,009 | 18,833 | 32,040 | |
| 1996 | R | 10,972 | 14,559 | 29,078 | |
| 1992 | R | 9,535 | 11,109 | 28,779 | |
| 1988 | R | 9,527 | 13,214 | 23,205 | |
| 1984 | R | 8,163 | 15,643 | 24,140 | |
| 1980 | R | 5,747 | 12,738 | 21,726 | |
| 1976 | R | 6,215 | 11,062 | 17,460 | |
| 1972 | R | 5,096 | 10,663 | 16,088 | |
| 1968 | R | 3,818 | 7,433 | 11,978 | |
| 1964 | R | 5,600 | 5,621 | 11,248 | |
| 1960 | R | 3,761 | 6,870 | 10,652 | |
| 1956 | R | 3,260 | 6,680 | 9,940 | |
| 1952 | R | 2,697 | 6,998 | 9,729 | |
| 1948 | R | 3,548 | 4,220 | 7,950 | |
| 1944 | D | 3,479 | 3,120 | 6,632 | |
| 1940 | D | 4,718 | 3,430 | 8,198 | |
| 1936 | D | 4,697 | 2,151 | 7,168 | |
| 1932 | D | 4,359 | 2,553 | 7,095 | |
| 1928 | R | 2,423 | 3,861 | 6,318 | |
| 1924 | R | 1,564 | 2,494 | 5,623 | |
| 1920 | R | 2,370 | 3,238 | 5,920 | |
| 1916 | D | 3,661 | 2,527 | 6,306 | |
| 1912 | D | 1,407 | 683 | 3,241 | |
| 1908 | R | 1,485 | 1,519 | 3,219 | |
| 1904 | R | 1,130 | 1,700 | 3,048 | |
| 1900 | D | 1,297 | 1,146 | 2,517 | |
| 1896 | D | 1,649 | 423 | 2,108 | |
| 1892 | D | 1,144 | 998 | 2,304 | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Gallatin County's political center of gravity has tracked its rapid population growth around Bozeman, flipping from reliably Republican to a narrow Democratic lean in presidential contests over the past decade.
The Democratic margin in Gallatin County has rarely exceeded fifty-eight points in modern history; the Republican margin has rarely exceeded forty-four points. 2024 delivered the county to the Democratic candidate by three points.
Gallatin County's demographics resemble the country more than they resemble most counties. A 89% non-Hispanic-white share, a 10% poverty rate, and a median household income of $93,528 — all within the broad national range. The county's voting pattern over the last decade is most similar to that of Teton County and Leelanau County.
