| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | D | 18,287 | 7,039 | 26,613 | |
| 2020 | D | 18,767 | 6,440 | 26,035 | |
| 2016 | D | 14,340 | 5,454 | 22,634 | |
| 2012 | D | 16,026 | 5,347 | 21,937 | |
| 2008 | D | 17,585 | 5,997 | 24,081 | |
| 2004 | D | 15,489 | 7,280 | 23,316 | |
| 2000 | D | 11,319 | 7,358 | 21,491 | |
| 1996 | D | 10,426 | 5,261 | 18,915 | |
| 1992 | D | 11,414 | 5,816 | 21,411 | |
| 1988 | D | 9,839 | 8,572 | 18,653 | |
| 1984 | R | 8,206 | 9,880 | 18,279 | |
| 1980 | R | 5,830 | 7,062 | 16,598 | |
| 1976 | R | 6,794 | 7,928 | 15,232 | |
| 1972 | R | 5,925 | 9,062 | 15,100 | |
| 1968 | R | 5,353 | 6,916 | 12,721 | |
| 1964 | D | 8,371 | 4,180 | 12,555 | |
| 1960 | R | 4,358 | 9,128 | 13,486 | |
| 1956 | R | 2,474 | 9,979 | 12,475 | |
| 1952 | R | 2,790 | 9,774 | 12,595 | |
| 1948 | R | 2,770 | 7,148 | 10,140 | |
| 1944 | R | 3,376 | 6,708 | 10,089 | |
| 1940 | R | 4,101 | 7,031 | 11,159 | |
| 1936 | R | 3,699 | 7,369 | 11,095 | |
| 1932 | R | 3,659 | 7,347 | 11,129 | |
| 1928 | R | 2,398 | 8,410 | 10,824 | |
| 1924 | R | 1,091 | 7,638 | 9,183 | |
| 1920 | R | 1,302 | 5,551 | 6,908 | |
| 1916 | R | 1,698 | 3,375 | 5,153 | |
| 1912 | R | 1,327 | 2,143 | 5,602 | |
| 1908 | R | 906 | 3,738 | 4,758 | |
| 1904 | R | 809 | 3,735 | 4,752 | |
| 1900 | R | 1,014 | 3,948 | 4,996 | |
| 1896 | R | 670 | 4,829 | 5,739 | |
| 1892 | R | 1,496 | 3,656 | 5,259 | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Windham County's mix of college towns, arts communities, and back-to-the-land settlers has made it Vermont's most reliably left-leaning county, with presidential margins that have widened steadily over the past two decades.
The unraveling was not abrupt. The Democratic margin in Windham County peaked at forty-nine points in 2012; it narrowed steadily over the late twentieth century. The 1988 election delivered the county to the Republican party for the first time in many years, by a margin of seven points. By 2024, the margin had widened further.
The economic and demographic context is severe. Windham County's median household income of $72,217 is among the lowest of any county in the United States; 12% of residents live below the federal poverty line. The county's voting pattern over the last decade is most similar to that of Coahoma County and Addison County.