| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | R | 209 | 1,984 | 2,215 | |
| 2020 | R | 214 | 2,124 | 2,359 | |
| 2016 | R | 222 | 1,965 | 2,248 | |
| 2012 | R | 301 | 1,792 | 2,093 | |
| 2008 | R | 346 | 1,857 | 2,203 | |
| 2004 | R | 408 | 1,843 | 2,251 | |
| 2000 | R | 599 | 1,607 | 2,220 | |
| 1996 | R | 816 | 1,179 | 2,301 | |
| 1992 | R | 845 | 1,244 | 2,782 | |
| 1988 | R | 963 | 1,543 | 2,551 | |
| 1984 | R | 664 | 2,098 | 2,777 | |
| 1980 | R | 826 | 1,943 | 2,876 | |
| 1976 | D | 1,540 | 1,230 | 2,825 | |
| 1972 | R | 626 | 2,106 | 2,816 | |
| 1968 | R | 773 | 1,508 | 2,821 | |
| 1964 | D | 1,617 | 1,438 | 3,055 | |
| 1960 | R | 1,082 | 2,115 | 3,197 | |
| 1956 | R | 1,448 | 1,896 | 3,344 | |
| 1952 | R | 1,281 | 2,583 | 3,864 | |
| 1948 | D | 2,049 | 1,494 | 3,543 | |
| 1944 | R | 1,808 | 2,166 | 3,987 | |
| 1940 | R | 2,391 | 2,613 | 5,038 | |
| 1936 | D | 2,980 | 1,846 | 4,863 | |
| 1932 | D | 3,855 | 1,051 | 4,906 | |
| 1928 | R | 1,175 | 2,486 | 3,804 | |
| 1924 | R | 1,126 | 1,539 | 3,464 | |
| 1920 | R | 995 | 1,738 | 3,358 | |
| 1916 | D | 992 | 796 | 2,711 | |
| 1912 | R | 1,075 | 1,086 | 2,953 | |
| 1908 | R | 1,075 | 1,210 | 2,780 | |
| 1904 | — | — | — | — | |
| 1900 | — | — | — | — | |
| 1896 | — | — | — | — | |
| 1892 | — | — | — | — | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Dewey County recorded an R+80.1 margin in 2024, placing it among the most one-sided counties in the state. Its sparse, ranching-dominated landscape and population of under 5,000 reflect a rural Great Plains demographic that has shifted heavily toward Republican candidates over recent cycles.
The Republican margin in Dewey County reached its widest at eighty-one points in 2020. The margin in 2024 was eighty points, in line with the county's deep historical pattern.
Dewey County's loyalty is rooted in its place. Median household income of $62,569, a 83% non-Hispanic-white share, and a population of 4,360 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 Stephens County and Wheeler County.
