| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | R | 1,680 | 2,055 | 3,914 | |
| 2020 | R | 1,910 | 1,996 | 4,017 | |
| 2016 | R | 1,560 | 1,797 | 3,652 | |
| 2012 | D | 2,086 | 1,514 | 3,672 | |
| 2008 | D | 2,564 | 1,473 | 4,150 | |
| 2004 | D | 2,195 | 1,762 | 4,028 | |
| 2000 | D | 2,059 | 1,605 | 3,813 | |
| 1996 | D | 2,118 | 1,209 | 3,997 | |
| 1992 | D | 1,827 | 1,212 | 4,193 | |
| 1988 | D | 2,083 | 1,957 | 4,118 | |
| 1984 | R | 1,962 | 2,431 | 4,464 | |
| 1980 | R | 1,504 | 2,298 | 4,160 | |
| 1976 | D | 2,061 | 1,822 | 3,928 | |
| 1972 | R | 1,464 | 2,304 | 3,907 | |
| 1968 | R | 1,771 | 1,947 | 3,885 | |
| 1964 | D | 2,463 | 1,612 | 4,078 | |
| 1960 | D | 2,227 | 1,876 | 4,132 | |
| 1956 | D | 2,205 | 1,985 | 4,190 | |
| 1952 | R | 1,466 | 1,998 | 3,483 | |
| 1948 | D | 1,820 | 1,142 | 3,128 | |
| 1944 | D | 1,848 | 1,281 | 3,168 | |
| 1940 | D | 2,418 | 1,503 | 3,982 | |
| 1936 | D | 2,923 | 1,052 | 4,109 | |
| 1932 | D | 2,263 | 965 | 3,500 | |
| 1928 | R | 1,296 | 1,630 | 2,949 | |
| 1924 | R | 389 | 965 | 2,468 | |
| 1920 | R | 555 | 1,624 | 2,279 | |
| 1916 | — | — | — | — | |
| 1912 | — | — | — | — | |
| 1908 | — | — | — | — | |
| 1904 | — | — | — | — | |
| 1900 | — | — | — | — | |
| 1896 | — | — | — | — | |
| 1892 | — | — | — | — | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Roosevelt County's Fort Peck Indian Reservation anchors a Native American voting bloc that has historically narrowed Republican margins here, making it an outlier among Montana's rural northeastern counties despite the R+9.6 result in 2024.
The Democratic margin in Roosevelt County has rarely exceeded forty-six points in modern history; the Republican margin has rarely exceeded forty-seven points. 2024 delivered the county to the Republican candidate by ten points.
Roosevelt County's demographics resemble the country more than they resemble most counties. A 33% non-Hispanic-white share, a 30% poverty rate, and a median household income of $57,063 — all within the broad national range. The county's voting pattern over the last decade is most similar to that of Vernon County and Crawford County.
