| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | D | 511,118 | 322,569 | 853,534 | |
| 2020 | D | 598,576 | 307,076 | 922,513 | |
| 2016 | D | 461,080 | 262,945 | 765,682 | |
| 2012 | D | 405,571 | 295,813 | 711,612 | |
| 2008 | D | 422,989 | 310,000 | 738,463 | |
| 2004 | R | 336,641 | 346,246 | 687,709 | |
| 2000 | R | 275,308 | 322,345 | 613,039 | |
| 1996 | R | 255,766 | 260,058 | 555,953 | |
| 1992 | R | 231,412 | 256,007 | 661,252 | |
| 1988 | R | 243,198 | 347,094 | 594,538 | |
| 1984 | R | 203,592 | 405,444 | 610,496 | |
| 1980 | R | 190,459 | 306,682 | 518,213 | |
| 1976 | R | 196,303 | 263,081 | 464,385 | |
| 1972 | R | 129,662 | 305,112 | 438,795 | |
| 1968 | R | 123,809 | 184,193 | 363,554 | |
| 1964 | D | 166,472 | 137,065 | 304,158 | |
| 1960 | R | 88,876 | 149,369 | 240,299 | |
| 1956 | R | 65,472 | 125,361 | 192,695 | |
| 1952 | R | 69,394 | 118,218 | 188,462 | |
| 1948 | D | 47,464 | 35,664 | 94,344 | |
| 1944 | D | 60,909 | 21,099 | 94,036 | |
| 1940 | D | 49,431 | 16,574 | 66,136 | |
| 1936 | D | 42,153 | 7,204 | 49,657 | |
| 1932 | D | 37,363 | 8,919 | 46,653 | |
| 1928 | R | 17,437 | 27,272 | 44,787 | |
| 1924 | D | 30,207 | 8,018 | 39,237 | |
| 1920 | D | 14,390 | 4,984 | 21,347 | |
| 1916 | D | 13,410 | 2,554 | 16,253 | |
| 1912 | D | 7,725 | 590 | 10,047 | |
| 1908 | — | — | — | — | |
| 1904 | — | — | — | — | |
| 1900 | — | — | — | — | |
| 1896 | — | — | — | — | |
| 1892 | — | — | — | — | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Dallas County's 2024 presidential margin of D+22.2 reflects a decade-long realignment driven by suburban college-educated voters and a growing Latino electorate, making it one of the anchor Democratic strongholds in a state Republicans still carry statewide.
The Democratic margin in Dallas County has been steady. It reached its modern peak at seventy-one points in 1912; the 2024 margin was twenty-two points, still in line with the county's long pattern.
Dallas County's political identity is inseparable from its demographic profile: a 35% non-Hispanic-white share, a median household income of $76,547, and the full diversity of a major metropolitan center. The county's voting pattern resembles other major urban centers most closely — Fairfax city and Fairfax County.