| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | D | 82,409 | 68,753 | 156,114 | |
| 2020 | D | 77,675 | 63,682 | 145,615 | |
| 2016 | R | 56,522 | 59,522 | 123,222 | |
| 2012 | R | 55,146 | 58,798 | 117,115 | |
| 2008 | R | 54,013 | 55,170 | 111,186 | |
| 2004 | R | 39,503 | 59,934 | 100,594 | |
| 2000 | R | 30,725 | 45,350 | 78,661 | |
| 1996 | R | 25,081 | 34,494 | 65,303 | |
| 1992 | R | 21,848 | 31,290 | 64,691 | |
| 1988 | R | 17,061 | 32,575 | 49,867 | |
| 1984 | R | 13,411 | 29,606 | 43,113 | |
| 1980 | R | 13,629 | 22,033 | 39,130 | |
| 1976 | R | 14,542 | 17,941 | 32,483 | |
| 1972 | R | 8,235 | 19,907 | 28,651 | |
| 1968 | R | 8,316 | 13,649 | 26,313 | |
| 1964 | D | 14,548 | 9,264 | 23,812 | |
| 1960 | R | 9,910 | 13,408 | 23,319 | |
| 1956 | R | 7,619 | 14,387 | 22,006 | |
| 1952 | R | 7,851 | 14,562 | 22,451 | |
| 1948 | R | 7,142 | 9,934 | 17,197 | |
| 1944 | R | 8,528 | 11,367 | 19,895 | |
| 1940 | D | 11,255 | 10,485 | 21,833 | |
| 1936 | D | 10,722 | 9,500 | 20,286 | |
| 1932 | D | 10,686 | 7,144 | 18,024 | |
| 1928 | R | 7,406 | 12,569 | 20,089 | |
| 1924 | R | 7,740 | 8,441 | 17,106 | |
| 1920 | R | 7,747 | 9,559 | 17,518 | |
| 1916 | D | 6,094 | 5,725 | 12,026 | |
| 1912 | D | 11,316 | 2,813 | 11,360 | |
| 1908 | D | 10,956 | 5,158 | 192 | |
| 1904 | D | 12,457 | 5,788 | 164 | |
| 1900 | R | 5,820 | 6,391 | 30 | |
| 1896 | R | 5,214 | 6,352 | 11,940 | |
| 1892 | D | 5,643 | 5,502 | 11,434 | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Frederick's population has grown roughly 20% since 2010, driven by spillover from the D.C. metro corridor, and that demographic churn has steadily eroded the Republican margins that once made it reliably red in statewide contests.
The Democratic margin in Frederick County has rarely exceeded 100 points in modern history; the Republican margin has rarely exceeded 100 points. 2024 delivered the county to the Democratic candidate by nine points.
Frederick County's demographics resemble the country more than they resemble most counties. A 68% non-Hispanic-white share, a 6% poverty rate, and a median household income of $122,002 — all within the broad national range. The county's voting pattern over the last decade is most similar to that of Kent County and Gwinnett County.
