| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | D | 63,454 | 26,145 | 92,097 | |
| 2020 | D | 62,171 | 25,579 | 89,498 | |
| 2016 | D | 49,341 | 25,614 | 77,420 | |
| 2012 | D | 48,774 | 25,178 | 75,222 | |
| 2008 | D | 43,635 | 25,732 | 70,126 | |
| 2004 | D | 29,354 | 28,442 | 58,241 | |
| 2000 | D | 21,873 | 21,768 | 44,592 | |
| 1996 | R | 15,890 | 17,432 | 35,823 | |
| 1992 | R | 14,498 | 17,293 | 38,454 | |
| 1988 | R | 11,823 | 20,828 | 32,764 | |
| 1984 | R | 10,264 | 16,132 | 26,460 | |
| 1980 | R | 8,887 | 11,807 | 22,020 | |
| 1976 | D | 9,525 | 7,792 | 17,317 | |
| 1972 | R | 4,502 | 9,665 | 14,353 | |
| 1968 | R | 4,247 | 4,645 | 12,065 | |
| 1964 | D | 6,546 | 3,455 | 10,001 | |
| 1960 | D | 5,482 | 4,560 | 10,042 | |
| 1956 | R | 3,931 | 5,088 | 9,019 | |
| 1952 | R | 3,338 | 4,334 | 7,721 | |
| 1948 | R | 1,878 | 2,703 | 4,621 | |
| 1944 | R | 1,875 | 2,755 | 4,630 | |
| 1940 | R | 2,692 | 2,716 | 5,464 | |
| 1936 | R | 2,597 | 2,623 | 5,284 | |
| 1932 | D | 2,473 | 1,851 | 4,371 | |
| 1928 | R | 1,860 | 2,522 | 4,391 | |
| 1924 | R | 1,491 | 2,215 | 3,914 | |
| 1920 | R | 1,642 | 2,585 | 4,270 | |
| 1916 | R | 1,363 | 1,374 | 2,859 | |
| 1912 | D | 2,871 | 1,573 | 2,646 | |
| 1908 | D | 2,870 | 1,167 | 61 | |
| 1904 | D | 3,662 | 1,659 | 31 | |
| 1900 | R | 1,368 | 2,268 | 7 | |
| 1896 | R | 1,372 | 2,117 | 3,529 | |
| 1892 | R | 1,051 | 1,279 | 2,391 | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Charles County's transformation from a conservative rural county to one of Maryland's most Democratic—driven by suburban growth and a majority-Black population now exceeding 45%—makes it one of the clearest examples of exurban demographic realignment on the East Coast.
The unraveling was not abrupt. The Democratic margin in Charles County peaked at 100 points in 1904; it narrowed steadily over the late twentieth century. The 2000 election delivered the county to the Republican party for the first time in many years, by a margin of zero points. By 2024, the margin had widened further.
The economic and demographic context is severe. Charles County's median household income of $122,816 is among the lowest of any county in the United States; 7% of residents live below the federal poverty line. The county's voting pattern over the last decade is most similar to that of Montgomery County and Mecklenburg County.