San Quentin leans heavily Democratic by roughly 42 points: about 71% of voters vote Democratic and 29% Republican.
About 37% of adults in San Quentin typically vote, below the U.S. average of about 62%. Among adults in San Quentin, ~26% vote Democratic, ~11% Republican, and ~63% don't vote. The map below shows estimated turnout by block group.
How San Quentin compares
Among cities within 25 miles, San Quentin leans more Democratic than 24 of 76 neighbors.
San Quentin runs about 21 points more Democratic than California as a whole.
Politics vary noticeably by neighborhood within San Quentin. The west side is the most Democratic-leaning (D+52) and the southwest side is the least Democratic-leaning (D+40), a spread of about 12 points.
Why San Quentin leans the way it does
This analysis examined 14,881 data points per city to find what predicts political lean and turnout. The items below are a few correlations that stood out for San Quentin, not a ranked or complete list of what matters most.
Dense areas vote Democratic. About 89% of residents in San Quentin live in densely developed areas, about 53 points above the U.S. average of 36%. A high never-married share predicts Democratic voting, and about 50% of adults in San Quentin have never been married, above 98% of cities.
Paved land cover and Democratic lean
Places with extensive paved surfaces tend to lean Democratic; San Quentin, CA sits in the top tenth nationally on this measure. Paved ground does not change how people vote; it mostly reflects how urban and built-up a place is.
Why turnout in San Quentin looks the way it does
Renters vote less often than owners. About 96% of households in San Quentin rent, about 71 points above the U.S. average of 25%. Low high-school completion lines up with lower turnout, and about 75% of adults in San Quentin have completed high school, below 96% of cities. Learn more about the findings and methodology on the political spectrum map.
Nearby Cities
- Corte Madera, CA D+56
- Larkspur, CA D+58
- Greenbrae, CA D+51
- Kentfield, CA D+54
- Belvedere-Tiburon, CA D+42
- Tiburon, CA D+44
- Mill Valley, CA D+55
- Ross, CA D+52
- San Rafael, CA D+46
- Tamalpais-Homestead Valley, CA D+62
Cities with Similar Populations
- Whitehall, NY R+40
- Peralta, NM R+17
- Constantine, MI R+42
- Joppa, MD R+23
- Shenandoah, TX R+26
- Sinking Spring, PA Even
- Dittmer, MO R+55
- Kaunakakai, HI D+17
- Yellville, AR R+57
- Clarkson, KY R+63
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Sources and methodology
Precinct-level voting records used to fit the model come from California Secretary of State, Elections, distributed by the Voting and Election Science Team. Demographic inputs come from the U.S. Census Bureau (ACS 5-year estimates and the 2020 Decennial Census). Health and environmental inputs come from the CDC (PLACES and the Environmental Justice Index). Land cover comes from the USGS and EPA. Election-day and lead-up weather come from PRISM 4km daily grids and the NOAA Global Historical Climatology Network. Mail-voting and election-administration patterns come from the MIT Election Lab's Survey of the Performance of American Elections. Block-group crime detail comes from CrimeGrade. Internet data and modeling support provided by ISPreports.org.
Modeling and analysis by the BestNeighborhood data science team. Full methodology and findings: political spectrum map.
Methodology reviewed by the BestNeighborhood data team. Last updated May 2026.