| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | R | 396 | 2,550 | 3,012 | |
| 2020 | R | 413 | 2,423 | 2,881 | |
| 2016 | R | 332 | 1,967 | 2,441 | |
| 2012 | R | 492 | 1,833 | 2,407 | |
| 2008 | R | 636 | 1,581 | 2,306 | |
| 2004 | R | 538 | 1,663 | 2,247 | |
| 2000 | R | 512 | 1,582 | 2,207 | |
| 1996 | R | 652 | 1,121 | 2,076 | |
| 1992 | R | 648 | 876 | 2,228 | |
| 1988 | R | 898 | 1,280 | 2,204 | |
| 1984 | R | 781 | 1,541 | 2,359 | |
| 1980 | R | 784 | 1,279 | 2,204 | |
| 1976 | R | 922 | 1,117 | 2,065 | |
| 1972 | R | 689 | 1,202 | 1,967 | |
| 1968 | R | 795 | 953 | 1,863 | |
| 1964 | D | 1,189 | 823 | 2,012 | |
| 1960 | R | 1,100 | 1,107 | 2,210 | |
| 1956 | R | 1,115 | 1,165 | 2,280 | |
| 1952 | R | 1,240 | 1,253 | 2,502 | |
| 1948 | D | 1,188 | 1,010 | 2,496 | |
| 1944 | D | 1,342 | 1,004 | 2,375 | |
| 1940 | D | 1,807 | 1,086 | 2,952 | |
| 1936 | D | 2,092 | 771 | 3,014 | |
| 1932 | D | 1,584 | 1,021 | 2,840 | |
| 1928 | R | 1,444 | 1,608 | 3,181 | |
| 1924 | R | 247 | 1,488 | 3,267 | |
| 1920 | R | 951 | 1,910 | 3,225 | |
| 1916 | D | 2,036 | 1,738 | 4,049 | |
| 1912 | R | 470 | 483 | 1,568 | |
| 1908 | — | — | — | — | |
| 1904 | — | — | — | — | |
| 1900 | — | — | — | — | |
| 1896 | — | — | — | — | |
| 1892 | — | — | — | — | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Musselshell County, anchored by the small ranching town of Roundup, recorded a 71.5-point Republican presidential margin in 2024—among the widest in a state already defined by its rural conservative lean.
The Democratic margin in Musselshell County peaked at forty-four points in 1936. By 1968 the county had flipped, voting Republican for the first time in many years. The 2024 margin was seventy-two points, the most Republican-leaning result in the county's modern history.
The economic context is the key. Musselshell County's median household income of $58,920 sits well below state and national norms, and 17% of residents live below the federal poverty line. The shift here is part of a broader realignment of working-class places across the country. The county's voting pattern over the last decade is most similar to that of Slope County and Logan County.