| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | R | 15,345 | 27,656 | 43,575 | |
| 2020 | R | 16,497 | 26,890 | 44,147 | |
| 2016 | R | 15,577 | 23,318 | 41,797 | |
| 2012 | D | 23,803 | 18,298 | 43,745 | |
| 2008 | D | 25,027 | 18,949 | 45,076 | |
| 2004 | D | 24,060 | 21,038 | 45,407 | |
| 2000 | D | 19,831 | 17,940 | 39,472 | |
| 1996 | D | 19,341 | 13,287 | 38,722 | |
| 1992 | D | 18,843 | 13,254 | 43,028 | |
| 1988 | D | 20,536 | 17,654 | 38,556 | |
| 1984 | R | 19,344 | 21,669 | 41,397 | |
| 1980 | R | 17,363 | 19,847 | 40,467 | |
| 1976 | D | 20,883 | 16,885 | 38,625 | |
| 1972 | R | 15,052 | 22,762 | 38,608 | |
| 1968 | R | 16,738 | 17,058 | 36,555 | |
| 1964 | D | 24,104 | 13,183 | 37,287 | |
| 1960 | R | 19,155 | 22,406 | 41,561 | |
| 1956 | R | 13,195 | 24,165 | 37,360 | |
| 1952 | R | 14,676 | 23,185 | 37,861 | |
| 1948 | R | 12,560 | 15,389 | 28,326 | |
| 1944 | R | 13,319 | 17,181 | 30,500 | |
| 1940 | R | 14,454 | 18,491 | 32,945 | |
| 1936 | D | 14,468 | 14,025 | 30,010 | |
| 1932 | R | 11,386 | 15,644 | 28,282 | |
| 1928 | R | 5,951 | 18,870 | 25,118 | |
| 1924 | R | 2,135 | 14,767 | 21,337 | |
| 1920 | R | 5,413 | 14,099 | 20,229 | |
| 1916 | R | 5,306 | 6,608 | 12,626 | |
| 1912 | D | 3,181 | 2,214 | 12,308 | |
| 1908 | R | 3,572 | 8,213 | 12,970 | |
| 1904 | R | 1,647 | 8,906 | 11,735 | |
| 1900 | R | 3,438 | 9,272 | 13,115 | |
| 1896 | R | 3,840 | 8,557 | 12,639 | |
| 1892 | R | 2,769 | 6,419 | 10,098 | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Once a Democratic stronghold anchored by union labor in its steel and chemical industries, Ashtabula County has shifted more than 40 margin points toward Republicans since 2004, tracing a pattern common across deindustrialized Great Lakes communities.
The county's recent history is a story of close margins. The Democratic margin reached twenty-nine points in 1964; the Republican margin reached sixty-two points in 1904. Most other elections have been decided by single-digit points.
Ashtabula County's demographics — a population of 97,167, a 89% non-Hispanic-white share, a median household income of $57,728 — 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 Henderson County and Chickasaw County.
