San Marino leans Democratic by roughly 22 points: about 61% of voters vote Democratic and 39% Republican.
About 75% of adults in San Marino typically vote, above the U.S. average of about 62%. Among adults in San Marino, ~46% vote Democratic, ~29% Republican, and ~25% don't vote. The map below shows estimated turnout by block group.
How San Marino compares
Among cities within 25 miles, San Marino leans more Democratic than 49 of 137 neighbors.
Politically, San Marino sits close to the rest of California.
Politics vary noticeably by neighborhood within San Marino. The west side is the most Democratic-leaning (D+44) and the north side is the least Democratic-leaning (D+13), a spread of about 30 points.
Why San Marino 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 Marino, not a ranked or complete list of what matters most.
Areas with high college attainment vote Democratic. About 84% of adults in San Marino hold a bachelor's degree, about 55 points above the U.S. average of 28%. Dense areas vote Democratic, and San Marino sits in the top fifth on density (more than 99%, in the top fraction of cities).
Preventive-care access and voter turnout
Places with strong routine preventive-care access tend to turn out at a higher rate; San Marino, CA sits in the top tenth nationally on this measure. Dental visits do not drive turnout; the rate reflects income, insurance, and healthcare access, which line up with who votes.
Why turnout in San Marino looks the way it does
Areas with strong routine healthcare access turn out at higher rates. San Marino is in the top quarter nationally for routine-care measures such as insurance coverage, preventive screenings, and dental visits. The dental-visit rate here is about 75%, about 15 points above the U.S. average of 60%. High high-school completion lines up with higher turnout, and about 98% of adults in San Marino have completed high school, above 93% of cities. Learn more about the findings and methodology on the political spectrum map.
Nearby Cities
- San Gabriel, CA D+19
- East Pasadena, CA D+33
- South Pasadena, CA D+52
- Pasadena, CA D+51
- Alhambra, CA D+28
- Temple City, CA D+13
- Rosemead, CA D+17
- Arcadia, CA D+14
- Kinneloa Mesa, CA D+16
- Sierra Madre, CA D+30
Cities with Similar Populations
- Holly Hill, FL Even
- Eufaula, AL Even
- Ball Ground, GA R+62
- Homosassa Springs, FL R+52
- Wesley Chapel, NC R+19
- Dallas, PA R+18
- Middle Valley, TN R+39
- McFarland, WI D+31
- St. Albans, VT R+12
- Excelsior Springs, MO R+35
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.