| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | D | 240,099 | 161,371 | 418,221 | |
| 2020 | D | 256,728 | 166,428 | 438,796 | |
| 2016 | D | 185,227 | 128,255 | 354,734 | |
| 2012 | D | 188,516 | 133,016 | 331,968 | |
| 2008 | D | 187,294 | 126,722 | 320,333 | |
| 2004 | D | 156,468 | 134,317 | 295,414 | |
| 2000 | D | 129,612 | 109,615 | 251,328 | |
| 1996 | D | 109,624 | 81,885 | 221,670 | |
| 1992 | D | 88,643 | 69,137 | 225,430 | |
| 1988 | R | 80,694 | 84,158 | 167,165 | |
| 1984 | R | 66,728 | 90,362 | 158,995 | |
| 1980 | R | 52,003 | 66,153 | 135,907 | |
| 1976 | D | 55,623 | 55,375 | 115,488 | |
| 1972 | R | 39,471 | 60,032 | 104,821 | |
| 1968 | D | 44,019 | 36,252 | 87,424 | |
| 1964 | D | 55,013 | 25,902 | 81,405 | |
| 1960 | D | 38,793 | 33,731 | 73,163 | |
| 1956 | D | 31,950 | 30,052 | 62,327 | |
| 1952 | D | 28,518 | 26,749 | 55,801 | |
| 1948 | D | 25,924 | 17,018 | 46,260 | |
| 1944 | D | 27,345 | 15,182 | 43,130 | |
| 1940 | D | 26,185 | 13,638 | 40,585 | |
| 1936 | D | 25,081 | 8,882 | 35,569 | |
| 1932 | D | 18,352 | 9,310 | 30,963 | |
| 1928 | R | 7,419 | 16,516 | 24,507 | |
| 1924 | R | 1,548 | 10,484 | 21,473 | |
| 1920 | R | 3,056 | 10,793 | 20,567 | |
| 1916 | R | 8,390 | 8,625 | 20,207 | |
| 1912 | D | 3,846 | 3,007 | 19,182 | |
| 1908 | R | 2,974 | 5,659 | 10,171 | |
| 1904 | R | 1,405 | 6,025 | 8,404 | |
| 1900 | R | 2,478 | 2,961 | 5,716 | |
| 1896 | D | 2,858 | 1,871 | 4,774 | |
| 1892 | R | 1,390 | 1,488 | 4,260 | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Home to Boeing's Everett assembly plant and a rapidly growing commuter belt north of Seattle, Snohomish County has shifted steadily toward Democrats over two decades as its white working-class base gave way to a more suburban, college-educated majority.
The Democratic margin in Snohomish County has been steady. It reached its modern peak at forty-six points in 1936; the 2024 margin was nineteen points, still in line with the county's long pattern.
Snohomish County's political identity is inseparable from its demographic profile: a 64% non-Hispanic-white share, a median household income of $111,246, and the full diversity of a major metropolitan center. The county's voting pattern resembles other major urban centers most closely — Ingham County and Cumberland County.
