| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | R | 389 | 676 | 1,088 | |
| 2020 | R | 466 | 694 | 1,183 | |
| 2016 | R | 412 | 666 | 1,149 | |
| 2012 | R | 548 | 626 | 1,203 | |
| 2008 | R | 557 | 614 | 1,208 | |
| 2004 | R | 759 | 833 | 1,630 | |
| 2000 | D | 712 | 377 | 1,116 | |
| 1996 | R | 507 | 539 | 1,145 | |
| 1992 | R | 413 | 556 | 1,197 | |
| 1988 | R | 579 | 663 | 1,262 | |
| 1984 | R | 453 | 856 | 1,316 | |
| 1980 | R | 350 | 919 | 1,324 | |
| 1976 | R | 481 | 610 | 1,111 | |
| 1972 | R | 476 | 808 | 1,286 | |
| 1968 | R | 457 | 665 | 1,233 | |
| 1964 | D | 775 | 624 | 1,399 | |
| 1960 | R | 607 | 779 | 1,386 | |
| 1956 | R | 685 | 746 | 1,431 | |
| 1952 | R | 516 | 873 | 1,389 | |
| 1948 | D | 758 | 477 | 1,252 | |
| 1944 | D | 566 | 494 | 1,060 | |
| 1940 | R | 860 | 915 | 1,775 | |
| 1936 | D | 807 | 530 | 1,349 | |
| 1932 | D | 1,410 | 453 | 1,908 | |
| 1928 | R | 544 | 766 | 1,317 | |
| 1924 | R | 102 | 444 | 778 | |
| 1920 | R | 199 | 220 | 452 | |
| 1916 | R | 67 | 222 | 297 | |
| 1912 | D | 179 | 0 | 253 | |
| 1908 | — | — | — | — | |
| 1904 | — | — | — | — | |
| 1900 | — | — | — | — | |
| 1896 | — | — | — | — | |
| 1892 | — | — | — | — | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Bennett County's large Lakota population — concentrated on the Rosebud Sioux Reservation — creates a distinct demographic mix rare in rural South Dakota, yet Republican margins at the county level have held in the mid-to-high double digits across recent cycles.
The Republican margin in Bennett County reached its widest at fifty-two points in 1916. The margin in 2024 was twenty-six points, in line with the county's deep historical pattern.
Bennett County's loyalty is rooted in its place. Median household income of $53,750, a 36% non-Hispanic-white share, and a population of 3,345 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 Lyman County and Jackson County.