San Marcos leans slightly Democratic by roughly 12 points: about 56% of voters vote Democratic and 44% Republican.
About 64% of adults in San Marcos typically vote, near the U.S. average of about 62%. Among adults in San Marcos, ~36% vote Democratic, ~28% Republican, and ~36% don't vote. The map below shows estimated turnout by block group.
How San Marcos compares
Among cities within 25 miles, San Marcos leans more Democratic than 18 of 26 neighbors.
San Marcos runs about 9 points more Republican than California as a whole.
Politics vary noticeably by neighborhood within San Marcos. The northwest side is the most Democratic-leaning (D+15) and the northeast side is the least Democratic-leaning (Even), a spread of about 14 points.
Why San Marcos 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 Marcos, not a ranked or complete list of what matters most.
Dense areas vote Democratic. About 82% of residents in San Marcos live in densely developed areas, about 46 points above the U.S. average of 36%. High college attainment predicts Democratic voting, and San Marcos sits in the top quarter (about 43%, above 90% of cities). A high never-married share predicts Democratic voting, and about 31% of adults in San Marcos have never been married, above 79% of cities.
Paved land cover and Democratic lean
Places with extensive paved surfaces tend to lean Democratic; San Marcos, 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 Marcos looks the way it does
Turnout in San Marcos sits close to the national pattern. Routine healthcare access, homeownership, education, and food security all land near their national averages here. Learn more about the findings and methodology on the political spectrum map.
Nearby Cities
- Vista, CA D+10
- Escondido, CA D+8
- Carlsbad, CA D+18
- Sunny Vista, CA D+15
- Encinitas, CA D+25
- Rancho Santa Fe, CA R+4
- Cardiff By The Sea, CA D+27
- Oceanside, CA D+9
- Bonsall, CA R+15
- Solana Beach, CA D+25
Cities with Similar Populations
- Rio Rancho, NM R+4
- Georgetown, TX R+15
- Edison, NJ D+12
- North Charleston, SC D+37
- Roswell, GA D+7
- Lees Summit, MO Even
- West Covina, CA D+20
- Fayetteville, AR D+17
- Davie, FL Even
- Gastonia, NC Even
All Local Stats
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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.