| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | R | 597 | 3,007 | 3,674 | |
| 2020 | R | 625 | 3,130 | 3,810 | |
| 2016 | R | 473 | 2,908 | 3,576 | |
| 2012 | R | 598 | 2,788 | 3,474 | |
| 2008 | R | 787 | 2,837 | 3,673 | |
| 2004 | R | 816 | 3,007 | 3,870 | |
| 2000 | R | 807 | 2,822 | 3,780 | |
| 1996 | R | 866 | 2,725 | 3,907 | |
| 1992 | R | 932 | 1,849 | 3,922 | |
| 1988 | R | 1,408 | 2,342 | 3,870 | |
| 1984 | R | 887 | 3,107 | 4,051 | |
| 1980 | R | 1,045 | 2,789 | 4,202 | |
| 1976 | R | 1,802 | 2,246 | 4,164 | |
| 1972 | R | 943 | 2,300 | 3,396 | |
| 1968 | R | 1,074 | 1,971 | 3,295 | |
| 1964 | D | 1,793 | 1,528 | 3,348 | |
| 1960 | R | 1,285 | 2,081 | 3,384 | |
| 1956 | R | 1,138 | 1,888 | 3,042 | |
| 1952 | R | 1,069 | 2,490 | 3,585 | |
| 1948 | R | 1,476 | 1,497 | 3,030 | |
| 1944 | R | 1,097 | 1,631 | 2,758 | |
| 1940 | R | 1,423 | 1,721 | 3,175 | |
| 1936 | D | 2,168 | 1,200 | 3,388 | |
| 1932 | D | 2,103 | 1,158 | 3,438 | |
| 1928 | R | 899 | 1,828 | 2,771 | |
| 1924 | R | 822 | 1,436 | 2,735 | |
| 1920 | R | 747 | 1,046 | 1,917 | |
| 1916 | D | 1,299 | 642 | 2,061 | |
| 1912 | D | 432 | 127 | 897 | |
| 1908 | D | 630 | 569 | 1,265 | |
| 1904 | R | 205 | 548 | 962 | |
| 1900 | D | 551 | 404 | 963 | |
| 1896 | D | 490 | 304 | 800 | |
| 1892 | R | 0 | 693 | 1,187 | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Thomas County, anchored by the small city of Colby on I-70, posted an R+65.8 margin in 2024, reflecting the deep Republican alignment typical of western Kansas's sparsely populated agricultural plains.
The Republican margin in Thomas County reached its widest at sixty-eight points in 2016. The margin in 2024 was sixty-six points, in line with the county's deep historical pattern.
Thomas County's loyalty is rooted in its place. Median household income of $71,325, a 90% non-Hispanic-white share, and a population of 7,885 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 Gray County and Hodgeman County.
