2024 results by precinct
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Margin—
Turnout—
Harris +50Trump +50
Real precinct boundaries. Hover for vote totals.
38 presidential elections
| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | D | 242,957 | 76,616 | 330,565 | |
| 2020 | D | 291,496 | 75,584 | 374,251 | |
| 2016 | D | 237,882 | 57,929 | 314,384 | |
| 2012 | D | 206,085 | 72,756 | 285,720 | |
| 2008 | D | 222,826 | 75,057 | 303,292 | |
| 2004 | D | 197,922 | 83,315 | 284,857 | |
| 2000 | D | 166,757 | 80,296 | 259,399 | |
| 1996 | D | 152,304 | 73,508 | 251,532 | |
| 1992 | D | 149,232 | 75,080 | 276,508 | |
| 1988 | D | 141,859 | 109,261 | 254,480 | |
| 1984 | R | 122,268 | 135,185 | 260,631 | |
| 1980 | R | 87,335 | 116,491 | 238,637 | |
| 1976 | R | 102,896 | 117,338 | 231,741 | |
| 1972 | R | 109,745 | 135,377 | 256,297 | |
| 1968 | D | 106,519 | 98,654 | 225,668 | |
| 1964 | D | 140,978 | 77,916 | 219,191 | |
| 1960 | R | 97,154 | 104,570 | 202,252 | |
| 1956 | R | 63,637 | 100,049 | 163,903 | |
| 1952 | R | 50,802 | 87,780 | 139,222 | |
| 1948 | R | 34,215 | 48,909 | 86,272 | |
| 1944 | D | 34,594 | 33,590 | 68,342 | |
| 1940 | D | 29,831 | 26,539 | 56,951 | |
| 1936 | D | 27,087 | 13,650 | 41,248 | |
| 1932 | D | 19,094 | 13,442 | 33,879 | |
| 1928 | R | 9,755 | 14,360 | 24,392 | |
| 1924 | R | 771 | 8,126 | 14,702 | |
| 1920 | R | 1,958 | 7,205 | 10,217 | |
| 1916 | R | 4,485 | 5,207 | 10,411 | |
| 1912 | D | 3,246 | 0 | 6,985 | |
| 1908 | R | 1,314 | 2,865 | 4,554 | |
| 1904 | R | 851 | 2,146 | 3,135 | |
| 1900 | R | 914 | 1,645 | 2,611 | |
| 1896 | R | 987 | 1,607 | 2,630 | |
| 1892 | R | 1,020 | 1,088 | 2,152 | |
| 1888 | R | 980 | 1,121 | 2,117 | |
| 1884 | R | 750 | 950 | 1,717 | |
| 1880 | R | 720 | 760 | 1,490 | |
| 1876 | R | 696 | 871 | 1,567 |
Demographics
Race, ethnicity, and ancestry
Click any group to see the ancestries typically reported within it.
American
100.0%
African American
1.7%
Multiple ancestry combinations reported; no single grouping above 1%.
American Indian, Alaska Native, Native Hawaiian, and Pacific Islander combined.
Source · American Community Survey 5-year estimates, 2024 release. Ancestry is a self-reported, multiple-response item; ancestry percentages do not sum to the parent race percentage.
Age distribution by sex
Median age: 40.9 in this county, 39.1 nationally
Male
Age
Female
85+
75–84
65–74
55–64
45–54
35–44
25–34
18–24
5–17
<5
Source · American Community Survey 5-year estimates, 2024 release.
Median household income
2024 inflation-adjusted dollars
$158,855
San Mateo County ranks in the top 0.5% of US counties.
San Mateo County$158,855
California$99,122
United States$80,734
Source · American Community Survey 5-year estimates, 2024 release.
Poverty rate
All persons below federal poverty line
6.7%
Children face moderate poverty.
Children under 1818.0%
Working age (18–64)100.0%
Seniors (65+)18.0%
Source · American Community Survey 5-year estimates, 2024 release.
Language at home
Population aged 5 and older
0.0%
speak English only
Source · ACS 5-year estimates, 2024.
Religious adherents
Adherents per capita by tradition
Source · 2020 US Religion Census. Remaining 66.2% of residents not counted as adherents by any reporting body.
San Mateo County sits between San Francisco and Silicon Valley, combining high housing costs and a highly educated workforce with some of the most consistent Democratic margins on the California coast.
The Democratic margin in San Mateo County has been steady. It reached its modern peak at fifty-eight points in 2020; the 2024 margin was fifty points, still in line with the county's long pattern.
San Mateo County's political identity is inseparable from its demographic profile: a 38% non-Hispanic-white share, a median household income of $158,855, and the full diversity of a major metropolitan center. The county's voting pattern resembles other major urban centers most closely — Marin County and Richmond city.
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