| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | R | 1,010 | 4,429 | 5,553 | |
| 2020 | R | 1,073 | 4,154 | 5,344 | |
| 2016 | R | 776 | 3,283 | 4,454 | |
| 2012 | R | 1,104 | 3,128 | 4,330 | |
| 2008 | R | 1,241 | 3,168 | 4,506 | |
| 2004 | R | 1,033 | 3,274 | 4,359 | |
| 2000 | R | 980 | 2,899 | 4,070 | |
| 1996 | R | 1,314 | 2,318 | 4,222 | |
| 1992 | R | 1,122 | 1,802 | 4,281 | |
| 1988 | R | 1,359 | 2,380 | 3,840 | |
| 1984 | R | 1,119 | 3,015 | 4,188 | |
| 1980 | R | 1,421 | 2,915 | 4,585 | |
| 1976 | R | 1,693 | 2,044 | 3,823 | |
| 1972 | R | 935 | 2,264 | 3,652 | |
| 1968 | R | 1,033 | 2,020 | 3,504 | |
| 1964 | D | 1,952 | 1,730 | 3,682 | |
| 1960 | R | 1,779 | 2,251 | 4,030 | |
| 1956 | R | 1,653 | 2,272 | 3,925 | |
| 1952 | R | 1,411 | 2,616 | 4,030 | |
| 1948 | R | 1,700 | 1,713 | 3,481 | |
| 1944 | R | 1,849 | 2,002 | 3,854 | |
| 1940 | D | 2,296 | 1,903 | 4,204 | |
| 1936 | D | 2,147 | 1,234 | 3,556 | |
| 1932 | D | 2,122 | 1,213 | 3,501 | |
| 1928 | R | 974 | 1,973 | 2,972 | |
| 1924 | R | 623 | 1,183 | 2,862 | |
| 1920 | R | 1,264 | 1,864 | 3,128 | |
| 1916 | D | 1,802 | 1,545 | 3,477 | |
| 1912 | D | 1,065 | 724 | 2,859 | |
| 1908 | R | 1,474 | 1,816 | 3,547 | |
| 1904 | R | 931 | 1,894 | 3,120 | |
| 1900 | D | 1,349 | 1,194 | 2,622 | |
| 1896 | D | 828 | 204 | 1,040 | |
| 1892 | R | 0 | 317 | 877 | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Washington County's sparse, agriculture-driven population anchors it among Idaho's most one-sided presidential counties, delivering R+61.7 in 2024 — a margin that has remained consistently wide across recent election cycles.
The Democratic margin in Washington County peaked at sixty points in 1896. By 1968 the county had flipped, voting Republican for the first time in many years. The 2024 margin was sixty-two points, the most Republican-leaning result in the county's modern history.
The economic context is the key. Washington County's median household income of $54,000 sits well below state and national norms, and 15% 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 Gooding County and Niobrara County.