| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | D | 841,372 | 593,270 | 1,478,028 | |
| 2020 | D | 964,650 | 600,094 | 1,602,143 | |
| 2016 | D | 735,476 | 477,766 | 1,311,618 | |
| 2012 | D | 626,957 | 536,726 | 1,193,949 | |
| 2008 | D | 666,581 | 541,032 | 1,235,503 | |
| 2004 | R | 526,437 | 596,033 | 1,136,351 | |
| 2000 | R | 437,666 | 475,736 | 958,634 | |
| 1996 | R | 389,964 | 402,876 | 884,151 | |
| 1992 | D | 367,397 | 352,125 | 986,646 | |
| 1988 | R | 333,264 | 523,143 | 869,195 | |
| 1984 | R | 257,029 | 502,344 | 769,267 | |
| 1980 | R | 195,410 | 435,910 | 716,866 | |
| 1976 | R | 263,654 | 353,302 | 633,795 | |
| 1972 | R | 206,455 | 371,627 | 601,137 | |
| 1968 | R | 167,669 | 261,540 | 464,863 | |
| 1964 | R | 211,808 | 214,445 | 426,286 | |
| 1960 | R | 171,259 | 223,056 | 395,421 | |
| 1956 | R | 106,716 | 195,742 | 303,605 | |
| 1952 | R | 101,880 | 175,281 | 278,751 | |
| 1948 | R | 98,217 | 101,552 | 205,459 | |
| 1944 | D | 89,959 | 75,746 | 166,764 | |
| 1940 | D | 71,188 | 55,434 | 128,110 | |
| 1936 | D | 64,628 | 35,686 | 101,854 | |
| 1932 | D | 45,622 | 35,305 | 85,150 | |
| 1928 | R | 22,749 | 47,769 | 71,151 | |
| 1924 | R | 2,944 | 22,726 | 46,391 | |
| 1920 | R | 8,478 | 19,826 | 31,087 | |
| 1916 | R | 16,815 | 16,978 | 36,537 | |
| 1912 | D | 9,731 | 0 | 21,728 | |
| 1908 | R | 2,393 | 5,412 | 9,403 | |
| 1904 | R | 1,398 | 4,303 | 7,230 | |
| 1900 | R | 2,678 | 3,800 | 6,921 | |
| 1896 | D | 3,908 | 3,631 | 7,748 | |
| 1892 | R | 2,334 | 3,525 | 7,712 | |
| 1888 | R | 3,189 | 4,661 | 8,194 | |
| 1884 | R | 800 | 1,120 | 1,965 | |
| 1880 | R | 546 | 743 | 1,308 | |
| 1876 | R | 668 | 794 | 1,462 |
San Diego County's political center of gravity has shifted steadily leftward over two decades, driven by a growing Latino population and college-educated suburban voters in communities like Chula Vista and Carlsbad. The 2024 margin of D+16.8 marks its widest Democratic spread yet.
The 2008 election was the turning point, when the Democratic candidate carried the county by ten points. The 2024 margin was seventeen points, in line with the county's new direction.
The demographics suggest why. A population of 3,288,774, a 48% non-Hispanic-white share, and a median household income of $106,268 situate the county in the broader realignment patterns of recent cycles. The county's voting pattern over the last decade is most similar to that of Ventura County and Arapahoe County.
