| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | R | 335 | 1,326 | 1,703 | |
| 2020 | R | 373 | 1,362 | 1,778 | |
| 2016 | R | 347 | 1,241 | 1,719 | |
| 2012 | R | 607 | 1,030 | 1,682 | |
| 2008 | R | 687 | 914 | 1,651 | |
| 2004 | R | 518 | 1,219 | 1,766 | |
| 2000 | R | 474 | 1,172 | 1,743 | |
| 1996 | R | 664 | 801 | 1,744 | |
| 1992 | R | 565 | 803 | 1,940 | |
| 1988 | R | 837 | 1,218 | 2,070 | |
| 1984 | R | 765 | 1,422 | 2,214 | |
| 1980 | R | 586 | 1,534 | 2,303 | |
| 1976 | D | 1,147 | 1,120 | 2,305 | |
| 1972 | R | 861 | 1,352 | 2,243 | |
| 1968 | R | 897 | 1,119 | 2,139 | |
| 1964 | D | 1,315 | 927 | 2,244 | |
| 1960 | R | 1,182 | 1,351 | 2,533 | |
| 1956 | R | 1,062 | 1,234 | 2,306 | |
| 1952 | R | 862 | 1,558 | 2,428 | |
| 1948 | D | 1,089 | 938 | 2,093 | |
| 1944 | D | 1,102 | 891 | 2,007 | |
| 1940 | D | 1,446 | 1,109 | 2,567 | |
| 1936 | D | 1,894 | 685 | 2,759 | |
| 1932 | D | 1,838 | 609 | 2,471 | |
| 1928 | D | 1,178 | 1,137 | 2,321 | |
| 1924 | R | 287 | 922 | 2,043 | |
| 1920 | R | 371 | 1,583 | 2,004 | |
| 1916 | D | 662 | 549 | 1,235 | |
| 1912 | D | 403 | 285 | 951 | |
| 1908 | R | 434 | 569 | 1,016 | |
| 1904 | R | 223 | 618 | 862 | |
| 1900 | R | 241 | 415 | 675 | |
| 1896 | R | 143 | 216 | 361 | |
| 1892 | R | 0 | 192 | 355 | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Foster County's small, rural population has delivered Republican presidential margins exceeding 55 points in recent cycles, reflecting the broader consolidation of agrarian Great Plains counties around a single party over the past two decades.
The Republican margin in Foster County reached its widest at sixty points in 1920. The margin in 2024 was fifty-eight points, in line with the county's deep historical pattern.
Foster County's loyalty is rooted in its place. Median household income of $87,831, a 94% non-Hispanic-white share, and a population of 3,358 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 Gage County and Roseau County.
