| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | R | 538 | 5,840 | 6,416 | |
| 2020 | R | 576 | 5,355 | 5,996 | |
| 2016 | R | 597 | 3,907 | 4,620 | |
| 2012 | R | 535 | 3,484 | 4,066 | |
| 2008 | R | 650 | 3,385 | 4,067 | |
| 2004 | R | 608 | 3,540 | 4,164 | |
| 2000 | R | 723 | 2,691 | 3,459 | |
| 1996 | R | 1,012 | 1,812 | 3,194 | |
| 1992 | R | 1,095 | 2,138 | 3,933 | |
| 1988 | R | 1,310 | 2,265 | 3,606 | |
| 1984 | R | 797 | 2,714 | 3,533 | |
| 1980 | R | 1,182 | 2,390 | 3,656 | |
| 1976 | D | 1,880 | 1,643 | 3,544 | |
| 1972 | R | 669 | 1,923 | 2,625 | |
| 1968 | R | 1,087 | 1,401 | 3,531 | |
| 1964 | D | 2,045 | 1,153 | 3,201 | |
| 1960 | R | 1,498 | 1,520 | 3,041 | |
| 1956 | D | 1,527 | 1,244 | 2,779 | |
| 1952 | D | 1,540 | 1,350 | 2,905 | |
| 1948 | D | 1,465 | 207 | 1,794 | |
| 1944 | D | 1,173 | 173 | 1,471 | |
| 1940 | D | 1,509 | 197 | 1,709 | |
| 1936 | D | 680 | 42 | 726 | |
| 1932 | D | 510 | 44 | 562 | |
| 1928 | R | 140 | 312 | 452 | |
| 1924 | D | 342 | 37 | 441 | |
| 1920 | D | 134 | 9 | 143 | |
| 1916 | D | 80 | 0 | 84 | |
| 1912 | D | 68 | 0 | 74 | |
| 1908 | — | — | — | — | |
| 1904 | — | — | — | — | |
| 1900 | — | — | — | — | |
| 1896 | — | — | — | — | |
| 1892 | — | — | — | — | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Gaines County, anchored by the small city of Seminole in the South Plains, recorded an R+82.6 presidential margin in 2024 — among the widest gaps of any Texas county — reflecting the oil-patch and agricultural economy that shapes its overwhelmingly Republican electorate.
The unraveling was not abrupt. The Democratic margin in Gaines County peaked at ninety-five points in 1916; it narrowed steadily over the late twentieth century. The 1980 election delivered the county to the Republican party for the first time in many years, by a margin of thirty-three points. By 2024, the margin had widened further.
The economic and demographic context is severe. Gaines County's median household income of $74,132 is among the lowest of any county in the United States; 7% of residents live below the federal poverty line. The county's voting pattern over the last decade is most similar to that of Alfalfa County and Martin County.