| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | R | 11,967 | 16,573 | 29,156 | |
| 2020 | R | 12,127 | 15,033 | 27,705 | |
| 2016 | R | 9,518 | 13,204 | 24,508 | |
| 2012 | R | 10,398 | 11,258 | 22,236 | |
| 2008 | D | 11,687 | 10,600 | 22,540 | |
| 2004 | R | 9,301 | 10,539 | 19,993 | |
| 2000 | R | 6,860 | 7,045 | 14,378 | |
| 1996 | D | 6,361 | 5,287 | 13,068 | |
| 1992 | D | 5,363 | 4,656 | 12,185 | |
| 1988 | R | 4,334 | 5,349 | 9,726 | |
| 1984 | R | 4,216 | 5,884 | 10,134 | |
| 1980 | D | 4,679 | 4,454 | 9,818 | |
| 1976 | D | 5,166 | 3,864 | 9,030 | |
| 1972 | R | 2,782 | 4,822 | 7,604 | |
| 1968 | D | 3,129 | 2,718 | 6,929 | |
| 1964 | D | 4,892 | 1,901 | 6,793 | |
| 1960 | D | 4,352 | 2,887 | 7,239 | |
| 1956 | R | 3,353 | 3,380 | 6,733 | |
| 1952 | D | 4,036 | 3,134 | 7,170 | |
| 1948 | D | 3,797 | 2,199 | 6,009 | |
| 1944 | D | 3,767 | 2,103 | 5,870 | |
| 1940 | D | 5,297 | 2,332 | 7,629 | |
| 1936 | D | 5,443 | 2,040 | 7,501 | |
| 1932 | D | 5,350 | 1,734 | 7,119 | |
| 1928 | D | 3,312 | 3,050 | 6,384 | |
| 1924 | D | 4,368 | 1,870 | 6,433 | |
| 1920 | D | 3,944 | 2,168 | 6,147 | |
| 1916 | D | 2,544 | 1,181 | 3,769 | |
| 1912 | D | 2,525 | 993 | 3,725 | |
| 1908 | D | 2,490 | 1,255 | 3,822 | |
| 1904 | D | 2,556 | 1,308 | 3,915 | |
| 1900 | R | 1,207 | 2,727 | 3,966 | |
| 1896 | D | 2,453 | 1,283 | 3,825 | |
| 1892 | D | 2,530 | 1,093 | 3,648 | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Jefferson County sits at West Virginia's northeastern tip, drawing Washington, D.C.-area commuters whose arrival has kept its presidential margins closer than the state's overwhelming statewide Republican lean—though 2024's R+15.7 result suggests that gap is narrowing.
The county's recent history is a story of close margins. The Democratic margin reached fifty-one points in 1932; the Republican margin reached thirty-eight points in 1900. Most other elections have been decided by single-digit points.
Jefferson County's demographics — a population of 59,260, a 81% non-Hispanic-white share, a median household income of $98,806 — 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 Lenawee County and Kankakee County.