| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | R | 1,522 | 4,965 | 6,712 | |
| 2020 | R | 1,496 | 4,869 | 6,507 | |
| 2016 | R | 1,202 | 4,269 | 5,840 | |
| 2012 | R | 1,640 | 4,257 | 6,071 | |
| 2008 | R | 1,933 | 4,108 | 6,232 | |
| 2004 | R | 1,582 | 4,425 | 6,127 | |
| 2000 | R | 1,352 | 4,353 | 5,994 | |
| 1996 | R | 1,866 | 3,671 | 6,194 | |
| 1992 | R | 1,615 | 2,736 | 6,490 | |
| 1988 | R | 2,052 | 3,948 | 6,116 | |
| 1984 | R | 1,804 | 4,585 | 6,459 | |
| 1980 | R | 1,840 | 4,455 | 6,852 | |
| 1976 | R | 2,470 | 3,556 | 6,160 | |
| 1972 | R | 1,652 | 4,082 | 6,049 | |
| 1968 | R | 2,070 | 3,367 | 6,057 | |
| 1964 | D | 3,300 | 2,980 | 6,293 | |
| 1960 | R | 2,999 | 3,294 | 6,306 | |
| 1956 | R | 2,757 | 3,771 | 6,528 | |
| 1952 | R | 2,271 | 4,402 | 6,691 | |
| 1948 | D | 3,059 | 2,411 | 5,652 | |
| 1944 | D | 3,164 | 2,229 | 5,422 | |
| 1940 | D | 3,873 | 2,706 | 6,619 | |
| 1936 | D | 4,675 | 1,821 | 6,745 | |
| 1932 | D | 4,470 | 2,400 | 7,136 | |
| 1928 | R | 2,667 | 4,109 | 6,838 | |
| 1924 | R | 1,580 | 2,942 | 7,642 | |
| 1920 | R | 3,371 | 5,858 | 9,727 | |
| 1916 | D | 5,749 | 3,290 | 9,424 | |
| 1912 | D | 1,393 | 745 | 3,663 | |
| 1908 | R | 1,112 | 1,529 | 2,916 | |
| 1904 | R | 780 | 1,599 | 2,529 | |
| 1900 | R | 913 | 1,228 | 2,157 | |
| 1896 | D | 834 | 725 | 1,562 | |
| 1892 | R | 560 | 766 | 1,378 | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Fergus County, anchored by the small city of Lewistown in the state's agricultural heartland, recorded a 51-point Republican presidential margin in 2024, reflecting the deep conservative alignment typical of Montana's sparsely populated central plains counties.
The Republican margin in Fergus County reached its widest at fifty-three points in 2016. The margin in 2024 was fifty-one points, in line with the county's deep historical pattern.
Fergus County's loyalty is rooted in its place. Median household income of $63,706, a 93% non-Hispanic-white share, and a population of 11,687 together describe a community whose political habits are deeply settled. The county's voting pattern over the last decade is most similar to that of Jackson County and Petroleum County.