San Mateo County, CA

CA · Presidential Elections 1876–2024

D+50.3
2024 Margin
R+7.4%
2020→2024 Swing
D since 1988
Voting Streak
742K
Population

San Mateo County, CA (California) voted D+50.3 for Kamala Harris (Democrat) in the 2024 presidential election, with Harris receiving 242,957 votes (73.5%) to 76,616 (23.18%) for Trump.

This represents a R+7.4% swing toward Republicans compared to 2020. San Mateo County is classified as a deep Democratic county. San Mateo County has voted Democratic in every presidential election since 1988. The county has a population of approximately 742,340.

Open in Cartographer

Interactive map with county profile in split-screen view

Quick Stats

2024 ResultD+50.3
2020→2024 SwingR+7.4%
Voting StreakD since 1988
Elections on Record38

Demographics

Population742,340
Median Age
40.9(US: 38.7)
College (BA+)
53.7%(US: 35.2%)
Median Income
$158,855(US: $80k)
White (non-Hisp)
35.8%(US: 57.6%)
Hispanic
24.9%(US: 19.1%)
Black
2.0%(US: 12.2%)
Asian
30.5%(US: 5.7%)
Homeownership
58.5%(US: 64.5%)
Poverty Rate
6.7%(US: 12.3%)
Veterans
2.9%(US: 6.2%)
Non-English (CVAP)
37.9%(US: 17.0%)
Source: Census ACS 5-Year (2020-2024)

Community Profile

Religious Composition

Source: Religion Census 2020
Catholic
21.1%
Evangelical
3.5%(Below Average)
Mainline Protestant
1.8%
LDS/Mormon
1.8%
Black Protestant
0.5%
+ 1 more traditions

Ancestry Groups

Source: Census ACS

Top reported ancestry groups (compared to national average).

Mexican
14.4%(1.3x)
Irish
6.6%
English
6.0%
German
6.0%
Italian
5.0%
American Heritage
2.8%
+ 4 more reported ancestry groups

Age Distribution

Median:40.9 yrs(US: 38.5)
Under 18
19.6%↓
18-29
7.3%↓
30-44
21.8%↑
45-64
33.5%↑
65+
17.8%
National average

Employment by Industry

Census ACS
Professional & TechnicalMajor Specialization
22.0%(1.8x US)
Retail Trade
8.5%(0.8x US)
Educational Services
7.8%
Manufacturing
7.5%(0.8x US)
Construction
5.4%(0.8x US)
Healthcare & Social Services
4.6%
National average
+ 1 more sectors

Presidential Elections

Presidential Results

YearDemocratRepublicanMarginSwing
202473.5%(242,957)23.2%(76,616)D+50.3R+7.4
202077.9%(291,496)20.2%(75,584)D+57.7D+0.5
201675.7%(237,882)18.4%(57,929)D+57.2D+10.6
201272.1%(206,085)25.5%(72,756)D+46.7R+2.1
200873.5%(222,826)24.8%(75,057)D+48.7D+8.5
200469.5%(197,922)29.3%(83,315)D+40.2D+6.9
200064.3%(166,757)30.9%(80,296)D+33.3D+2.0
199660.5%(152,304)29.2%(73,508)D+31.3D+4.5
199254.0%(149,232)27.1%(75,080)D+26.8D+14.0
198855.7%(141,859)42.9%(109,261)D+12.8D+17.8

Source: Official state election returns via MIT Election Data + Science Lab

Presidential Margin Trend

San Mateo County, CA • 1876–2024

D+R++60+40+200-20-40-601876188418921900190819161924193219401948195619641972198019881996200420122020
Democratic margin
Republican margin

Senate Elections

Senate Results

YearDemocratRepublicanMarginSwing
202473.7%(237,186)26.3%(84,474)D+47.5R+50.5
201898.0%(262,406)0.0%(0)D+98.0R+4.7
2016102.7%(288,662)0.0%(0)D+102.7D+48.3
201277.2%(213,503)22.8%(62,979)D+54.4R+0.2
200674.8%(152,082)20.2%(41,043)D+54.6D+19.7
200064.8%(165,216)29.9%(76,273)D+34.9D+0.6
199464.2%(136,686)29.9%(63,702)D+34.3R+5.1
199267.3%(181,990)27.9%(75,470)D+39.4D+33.5
198851.1%(125,724)45.2%(111,187)D+5.9D+8.1
198247.0%(98,862)49.2%(103,493)R+2.2D+0.8

Source: Official state election returns via MIT Election Data + Science Lab

Governor Elections

Governor Results

YearDemocratRepublicanMarginSwing
202275.0%(185,599)25.0%(61,918)D+50.0R+0.5
201875.2%(213,282)24.8%(70,242)D+50.5D+0.0
201475.2%(120,280)24.8%(39,615)D+50.4D+15.9
201065.7%(145,970)31.1%(69,212)D+34.5D+34.2
200647.4%(97,092)47.1%(96,478)D+0.3R+27.8
200258.0%(99,803)29.9%(51,497)D+28.1R+11.9
199868.4%(142,144)28.5%(59,249)D+39.9D+38.3
199449.2%(106,391)47.6%(102,989)D+1.6R+13.4
199055.4%(109,963)40.5%(80,253)D+15.0D+40.6
198636.2%(71,329)61.8%(121,910)R+25.7R+29.8

Source: Official state election returns via MIT Election Data + Science Lab

ShareShareShare

Explore More

CA ResultsBiggest Swings 2024Flipped Counties 2024Bellwether CountiesNational Swing Map