| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | D | 49,121 | 39,467 | 90,924 | |
| 2020 | D | 49,491 | 39,692 | 91,385 | |
| 2016 | D | 36,268 | 35,668 | 80,129 | |
| 2012 | D | 39,338 | 36,832 | 78,316 | |
| 2008 | D | 38,711 | 36,202 | 76,470 | |
| 2004 | R | 33,285 | 37,371 | 71,575 | |
| 2000 | R | 25,822 | 30,641 | 59,392 | |
| 1996 | R | 22,857 | 22,860 | 52,044 | |
| 1992 | R | 19,039 | 23,404 | 56,662 | |
| 1988 | R | 19,423 | 27,683 | 47,504 | |
| 1984 | R | 16,335 | 28,129 | 44,823 | |
| 1980 | R | 13,983 | 22,704 | 40,911 | |
| 1976 | R | 14,676 | 24,030 | 39,617 | |
| 1972 | R | 9,817 | 23,806 | 34,521 | |
| 1968 | R | 13,417 | 17,292 | 31,840 | |
| 1964 | D | 16,195 | 12,699 | 28,950 | |
| 1960 | R | 10,918 | 16,080 | 27,065 | |
| 1956 | R | 7,172 | 13,789 | 21,012 | |
| 1952 | R | 6,792 | 14,566 | 21,447 | |
| 1948 | D | 9,155 | 8,131 | 17,467 | |
| 1944 | R | 6,873 | 8,355 | 15,274 | |
| 1940 | R | 8,393 | 9,096 | 17,551 | |
| 1936 | D | 8,958 | 5,316 | 14,919 | |
| 1932 | D | 7,340 | 5,254 | 12,874 | |
| 1928 | R | 4,720 | 8,334 | 13,098 | |
| 1924 | R | 857 | 5,722 | 10,127 | |
| 1920 | R | 1,756 | 7,130 | 9,245 | |
| 1916 | R | 1,926 | 2,101 | 4,230 | |
| 1912 | D | 1,542 | 720 | 3,953 | |
| 1908 | R | 1,621 | 2,472 | 4,260 | |
| 1904 | R | 1,140 | 2,745 | 4,005 | |
| 1900 | R | 1,597 | 2,818 | 4,573 | |
| 1896 | R | 1,741 | 3,201 | 5,095 | |
| 1892 | D | 2,344 | 1,931 | 4,615 | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Olmsted County's economy and population are unusually concentrated around Rochester's health-care sector, drawing a highly educated workforce that has pushed the county's presidential margins toward Democrats by roughly ten points in recent cycles.
The Democratic margin in Olmsted County has rarely exceeded twenty-four points in modern history; the Republican margin has rarely exceeded fifty-eight points. 2024 delivered the county to the Democratic candidate by eleven points.
Olmsted County's demographics resemble the country more than they resemble most counties. A 77% non-Hispanic-white share, a 8% poverty rate, and a median household income of $95,406 — all within the broad national range. The county's voting pattern over the last decade is most similar to that of Hamilton County and Yakutat City and Borough.