| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | R | 10,806 | 24,326 | 36,253 | |
| 2020 | R | 11,819 | 24,764 | 37,680 | |
| 2016 | R | 7,810 | 18,518 | 29,258 | |
| 2012 | R | 8,950 | 17,852 | 27,829 | |
| 2008 | R | 9,601 | 17,153 | 27,438 | |
| 2004 | R | 7,779 | 17,799 | 25,995 | |
| 2000 | R | 7,073 | 15,830 | 23,798 | |
| 1996 | R | 8,065 | 10,895 | 21,866 | |
| 1992 | R | 7,278 | 9,503 | 21,921 | |
| 1988 | R | 7,564 | 10,859 | 18,799 | |
| 1984 | R | 6,298 | 12,888 | 19,584 | |
| 1980 | R | 5,673 | 11,152 | 18,196 | |
| 1976 | R | 7,777 | 9,192 | 17,721 | |
| 1972 | R | 5,487 | 9,370 | 15,814 | |
| 1968 | R | 5,773 | 7,007 | 14,367 | |
| 1964 | D | 8,352 | 6,065 | 14,427 | |
| 1960 | R | 7,400 | 7,568 | 15,005 | |
| 1956 | D | 6,938 | 6,603 | 13,549 | |
| 1952 | R | 4,381 | 4,512 | 8,915 | |
| 1948 | D | 4,067 | 2,081 | 6,277 | |
| 1944 | D | 2,354 | 1,530 | 3,902 | |
| 1940 | D | 4,097 | 1,487 | 5,601 | |
| 1936 | D | 4,560 | 694 | 5,328 | |
| 1932 | D | 1,376 | 840 | 2,410 | |
| 1928 | R | 641 | 1,407 | 2,067 | |
| 1924 | R | 332 | 813 | 1,989 | |
| 1920 | R | 684 | 1,378 | 2,366 | |
| 1916 | D | 1,563 | 1,205 | 3,030 | |
| 1912 | D | 771 | 458 | 2,630 | |
| 1908 | — | — | — | — | |
| 1904 | — | — | — | — | |
| 1900 | — | — | — | — | |
| 1896 | — | — | — | — | |
| 1892 | — | — | — | — | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Grant County's economy pivots on the Columbia Basin Project's irrigated agriculture, and its electorate reflects that rural, agricultural identity — the 2024 presidential margin landed at R+37.3, among the wider gaps in Washington state.
The Democratic margin in Grant County peaked at seventy-three points in 1936. By 1968 the county had flipped, voting Republican for the first time in many years. The 2024 margin was thirty-seven points, the most Republican-leaning result in the county's modern history.
The economic context is the key. Grant County's median household income of $73,267 sits well below state and national norms, and 16% of residents live below the federal poverty line. The shift here is part of a broader realignment of working-class places across the country. The county's voting pattern over the last decade is most similar to that of Klamath County and Grant County.