| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | D | 126,767 | 125,566 | 256,544 | |
| 2020 | D | 135,064 | 129,034 | 268,505 | |
| 2016 | R | 122,016 | 123,909 | 261,989 | |
| 2012 | D | 137,139 | 124,841 | 267,936 | |
| 2008 | D | 145,997 | 128,679 | 279,031 | |
| 2004 | D | 142,997 | 138,371 | 282,584 | |
| 2000 | D | 114,597 | 109,792 | 230,987 | |
| 1996 | D | 115,469 | 95,391 | 230,957 | |
| 1992 | D | 108,017 | 104,751 | 261,720 | |
| 1988 | R | 95,737 | 131,596 | 228,943 | |
| 1984 | R | 94,016 | 137,053 | 232,402 | |
| 1980 | D | 105,110 | 101,443 | 223,009 | |
| 1976 | D | 106,468 | 100,223 | 211,436 | |
| 1972 | R | 82,231 | 120,998 | 208,552 | |
| 1968 | D | 96,082 | 84,766 | 207,120 | |
| 1964 | D | 126,633 | 71,979 | 198,612 | |
| 1960 | R | 98,325 | 109,602 | 207,927 | |
| 1956 | R | 76,270 | 107,278 | 183,548 | |
| 1952 | R | 79,860 | 91,905 | 171,765 | |
| 1948 | D | 76,879 | 60,048 | 138,114 | |
| 1944 | D | 82,367 | 63,336 | 145,703 | |
| 1940 | D | 86,084 | 57,866 | 143,950 | |
| 1936 | D | 76,430 | 44,742 | 127,778 | |
| 1932 | D | 51,270 | 49,267 | 105,717 | |
| 1928 | R | 38,517 | 71,279 | 110,461 | |
| 1924 | R | 21,860 | 50,845 | 81,210 | |
| 1920 | R | 38,433 | 46,493 | 89,975 | |
| 1916 | D | 24,339 | 19,683 | 46,875 | |
| 1912 | D | 15,544 | 10,341 | 39,538 | |
| 1908 | D | 20,566 | 20,069 | 42,615 | |
| 1904 | R | 13,933 | 22,144 | 37,725 | |
| 1900 | R | 16,236 | 19,606 | 36,614 | |
| 1896 | R | 15,540 | 18,333 | 34,232 | |
| 1892 | D | 14,067 | 13,197 | 28,152 | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Once reliably Democratic thanks to Dayton's union-heavy workforce, Montgomery County has shifted toward razor-thin margins, posting a D+0.5 result in 2024 as suburban realignment and post-industrial demographic change pulled it toward equilibrium.
The county's recent history is a story of close margins. The Democratic margin reached twenty-eight points in 1964; the Republican margin reached thirty-six points in 1924. Most other elections have been decided by single-digit points.
Montgomery County's demographics — a population of 536,096, a 68% non-Hispanic-white share, a median household income of $66,139 — 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 Pinellas County and Merrimack County.
