| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | D | 179,600 | 63,426 | 251,465 | |
| 2020 | D | 199,938 | 61,825 | 268,317 | |
| 2016 | D | 160,435 | 51,408 | 233,303 | |
| 2012 | D | 153,942 | 54,784 | 216,865 | |
| 2008 | D | 168,888 | 55,127 | 229,351 | |
| 2004 | D | 148,261 | 68,204 | 220,690 | |
| 2000 | D | 117,295 | 63,529 | 197,006 | |
| 1996 | D | 100,738 | 53,555 | 181,297 | |
| 1992 | D | 104,334 | 47,619 | 197,691 | |
| 1988 | D | 91,262 | 67,725 | 161,583 | |
| 1984 | R | 71,295 | 76,447 | 149,657 | |
| 1980 | R | 45,596 | 60,722 | 125,985 | |
| 1976 | R | 50,353 | 50,555 | 105,952 | |
| 1972 | R | 43,746 | 57,697 | 105,434 | |
| 1968 | R | 33,587 | 38,088 | 78,059 | |
| 1964 | D | 44,354 | 27,677 | 72,136 | |
| 1960 | R | 29,147 | 34,641 | 64,032 | |
| 1956 | R | 20,616 | 33,659 | 54,361 | |
| 1952 | R | 17,046 | 34,088 | 51,717 | |
| 1948 | R | 16,026 | 22,077 | 39,984 | |
| 1944 | R | 15,949 | 16,309 | 32,369 | |
| 1940 | R | 15,230 | 16,819 | 32,379 | |
| 1936 | D | 17,273 | 11,185 | 28,706 | |
| 1932 | D | 15,686 | 9,161 | 25,669 | |
| 1928 | R | 8,506 | 12,891 | 21,591 | |
| 1924 | R | 1,767 | 9,535 | 17,028 | |
| 1920 | R | 4,070 | 10,377 | 15,512 | |
| 1916 | R | 8,377 | 9,733 | 19,324 | |
| 1912 | D | 6,500 | 0 | 14,199 | |
| 1908 | R | 3,168 | 5,427 | 9,439 | |
| 1904 | R | 2,816 | 5,269 | 8,548 | |
| 1900 | R | 3,517 | 4,381 | 8,107 | |
| 1896 | R | 3,595 | 4,053 | 7,816 | |
| 1892 | D | 3,451 | 3,016 | 6,950 | |
| 1888 | D | 3,394 | 3,293 | 7,011 | |
| 1884 | R | 2,944 | 3,044 | 6,160 | |
| 1880 | D | 2,628 | 2,290 | 5,040 | |
| 1876 | D | 2,907 | 2,432 | 5,345 |
Sonoma's blend of agricultural heritage and coastal-influenced professional demographics anchors one of California's most consistent Democratic strongholds, with presidential margins widening steadily over the past two decades.
The unraveling was not abrupt. The Democratic margin in Sonoma County peaked at fifty-one points in 2020; it narrowed steadily over the late twentieth century. The 1988 election delivered the county to the Republican party for the first time in many years, by a margin of fifteen points. By 2024, the margin had widened further.
The economic and demographic context is severe. Sonoma County's median household income of $104,674 is among the lowest of any county in the United States; 9% of residents live below the federal poverty line. The county's voting pattern over the last decade is most similar to that of Santa Cruz County and Marin County.
