| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | R | 50,636 | 61,249 | 113,233 | |
| 2020 | R | 57,641 | 59,903 | 118,966 | |
| 2016 | D | 57,381 | 53,616 | 117,636 | |
| 2012 | D | 77,059 | 42,641 | 122,801 | |
| 2008 | D | 79,173 | 45,319 | 127,659 | |
| 2004 | D | 83,194 | 48,761 | 132,904 | |
| 2000 | D | 69,212 | 40,460 | 114,119 | |
| 1996 | D | 72,716 | 31,397 | 118,178 | |
| 1992 | D | 64,731 | 31,191 | 125,650 | |
| 1988 | D | 75,524 | 43,722 | 120,126 | |
| 1984 | D | 76,514 | 53,424 | 131,438 | |
| 1980 | D | 63,677 | 50,153 | 125,161 | |
| 1976 | D | 75,837 | 46,314 | 125,294 | |
| 1972 | R | 62,428 | 64,144 | 129,088 | |
| 1968 | D | 68,433 | 42,948 | 123,578 | |
| 1964 | D | 90,934 | 33,775 | 124,709 | |
| 1960 | D | 82,143 | 51,927 | 134,070 | |
| 1956 | R | 59,126 | 63,992 | 123,118 | |
| 1952 | D | 67,722 | 53,164 | 120,886 | |
| 1948 | D | 62,468 | 37,365 | 101,146 | |
| 1944 | D | 70,102 | 35,184 | 105,286 | |
| 1940 | D | 76,441 | 37,496 | 113,937 | |
| 1936 | D | 64,886 | 24,825 | 90,858 | |
| 1932 | R | 33,139 | 39,713 | 75,861 | |
| 1928 | R | 26,928 | 48,341 | 75,748 | |
| 1924 | R | 9,335 | 37,647 | 55,264 | |
| 1920 | R | 14,941 | 29,736 | 46,570 | |
| 1916 | D | 13,013 | 11,256 | 25,225 | |
| 1912 | D | 6,838 | 5,839 | 20,703 | |
| 1908 | R | 9,312 | 10,760 | 21,023 | |
| 1904 | R | 4,436 | 10,404 | 17,350 | |
| 1900 | R | 7,402 | 8,939 | 16,686 | |
| 1896 | R | 6,772 | 8,529 | 15,432 | |
| 1892 | D | 6,358 | 5,806 | 12,750 | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Mahoning County, anchored by Youngstown, spent decades as one of Ohio's most reliably Democratic counties; since 2016 it has shifted sharply, posting an R+9.4 margin in 2024 after deindustrialization reshaped its working-class electorate.
The county's recent history is a story of close margins. The Democratic margin reached forty-six points in 1964; the Republican margin reached fifty-one points in 1924. Most other elections have been decided by single-digit points.
Mahoning County's demographics — a population of 226,491, a 75% non-Hispanic-white share, a median household income of $56,942 — 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 Carlton County and Mower County.