| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | R | 44,910 | 75,929 | 121,956 | |
| 2020 | R | 45,088 | 72,080 | 118,478 | |
| 2016 | R | 36,322 | 61,386 | 102,267 | |
| 2012 | R | 40,345 | 53,230 | 94,978 | |
| 2008 | R | 46,122 | 50,752 | 98,047 | |
| 2004 | D | 48,225 | 47,673 | 96,177 | |
| 2000 | D | 44,961 | 37,339 | 84,441 | |
| 1996 | D | 40,952 | 27,777 | 77,745 | |
| 1992 | D | 46,143 | 21,977 | 84,364 | |
| 1988 | D | 47,527 | 28,651 | 76,553 | |
| 1984 | D | 50,911 | 34,782 | 85,937 | |
| 1980 | D | 45,295 | 32,532 | 82,018 | |
| 1976 | D | 49,317 | 32,827 | 83,251 | |
| 1972 | R | 34,781 | 42,587 | 78,862 | |
| 1968 | D | 47,805 | 28,023 | 84,968 | |
| 1964 | D | 63,482 | 24,127 | 87,756 | |
| 1960 | D | 53,729 | 38,348 | 92,197 | |
| 1956 | D | 48,052 | 39,465 | 87,615 | |
| 1952 | D | 55,725 | 36,041 | 92,036 | |
| 1948 | D | 46,327 | 26,860 | 75,166 | |
| 1944 | D | 46,023 | 27,615 | 74,030 | |
| 1940 | D | 50,829 | 29,026 | 80,151 | |
| 1936 | D | 52,878 | 23,342 | 77,168 | |
| 1932 | D | 28,934 | 21,447 | 52,536 | |
| 1928 | R | 17,149 | 31,099 | 48,893 | |
| 1924 | R | 6,706 | 22,315 | 36,797 | |
| 1920 | R | 8,827 | 18,514 | 29,625 | |
| 1916 | R | 7,747 | 10,367 | 19,788 | |
| 1912 | D | 5,563 | 4,297 | 18,697 | |
| 1908 | R | 7,018 | 11,430 | 20,298 | |
| 1904 | R | 4,886 | 11,530 | 17,467 | |
| 1900 | R | 6,380 | 10,408 | 17,521 | |
| 1896 | R | 7,384 | 10,798 | 18,640 | |
| 1892 | R | 6,847 | 8,060 | 15,729 | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Washington County's coal and steel heritage built one of Pennsylvania's strongest Democratic machines, but the county has shifted sharply rightward over two decades, delivering a 25-point Republican margin in 2024.
The 2008 election was the turning point, when the Republican candidate carried the county by five points. The 2024 margin was twenty-five points, in line with the county's new direction.
The demographics suggest why. A population of 210,042, a 90% non-Hispanic-white share, and a median household income of $78,958 situate the county in the broader realignment patterns of recent cycles. The county's voting pattern over the last decade is most similar to that of Fayette County and Fayette County.
