| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | R | 12,317 | 12,484 | 25,221 | |
| 2020 | D | 12,390 | 11,508 | 24,444 | |
| 2016 | R | 10,210 | 10,796 | 22,683 | |
| 2012 | D | 12,166 | 9,269 | 21,837 | |
| 2008 | D | 13,249 | 9,169 | 22,614 | |
| 2004 | D | 11,434 | 10,142 | 21,804 | |
| 2000 | R | 8,224 | 9,304 | 18,668 | |
| 1996 | D | 8,380 | 6,824 | 17,260 | |
| 1992 | D | 7,921 | 6,318 | 17,799 | |
| 1988 | R | 6,378 | 8,836 | 15,283 | |
| 1984 | R | 4,962 | 9,220 | 14,239 | |
| 1980 | R | 4,889 | 7,472 | 14,137 | |
| 1976 | R | 6,323 | 6,679 | 13,207 | |
| 1972 | R | 5,554 | 7,901 | 13,592 | |
| 1968 | R | 5,817 | 6,094 | 12,328 | |
| 1964 | D | 8,787 | 3,975 | 12,762 | |
| 1960 | R | 6,469 | 7,105 | 13,574 | |
| 1956 | R | 4,239 | 8,403 | 12,647 | |
| 1952 | R | 4,743 | 8,317 | 13,060 | |
| 1948 | R | 4,696 | 6,003 | 10,818 | |
| 1944 | D | 5,972 | 5,935 | 11,913 | |
| 1940 | D | 5,872 | 5,583 | 11,455 | |
| 1936 | R | 5,113 | 5,347 | 10,538 | |
| 1932 | R | 4,368 | 5,153 | 9,579 | |
| 1928 | R | 3,549 | 5,754 | 9,346 | |
| 1924 | R | 2,268 | 5,187 | 7,625 | |
| 1920 | R | 2,521 | 4,647 | 7,222 | |
| 1916 | D | 2,215 | 2,193 | 4,446 | |
| 1912 | R | 1,523 | 1,677 | 4,317 | |
| 1908 | R | 1,469 | 2,758 | 4,363 | |
| 1904 | R | 1,447 | 2,774 | 4,320 | |
| 1900 | R | 1,538 | 2,559 | 4,166 | |
| 1896 | R | 865 | 2,750 | 3,849 | |
| 1892 | R | 2,021 | 2,434 | 4,521 | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Sullivan County's 2024 presidential margin of R+0.7 makes it a genuine bellwether in a state already defined by razor-thin statewide results. Its mix of small mill towns and rural hill communities produces an electorate that resists easy categorization.
The county's recent history is a story of close margins. The Democratic margin reached thirty-eight points in 1964; the Republican margin reached forty-nine points in 1896. Most other elections have been decided by single-digit points.
Sullivan County's demographics — a population of 43,715, a 92% non-Hispanic-white share, a median household income of $80,858 — situate the county close to national averages on several dimensions. The county's voting pattern over the last decade is most similar to that of Winnebago County and Orleans County.