San Marcos, TX Political Map | Democrat & Republican Areas in San Marcos

By the BestNeighborhood data science team. Last updated May 2026.

San Marcos leans Democratic by roughly 20 points: about 60% of voters vote Democratic and 40% Republican.

 

About 47% of adults in San Marcos typically vote, below the U.S. average of about 62%. Among adults in San Marcos, ~28% vote Democratic, ~19% Republican, and ~53% 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 38 of 42 neighbors.

San Marcos runs about 34 points more Democratic than Texas as a whole. Texas leans Republican overall, while San Marcos is one of the few Democratic-leaning pockets.

Politics vary noticeably by neighborhood within San Marcos. The north side runs the most Democratic (D+43) and the southeast side runs the most Republican (Even), a spread of about 44 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 62% of residents in San Marcos live in densely developed areas, about 26 points above the U.S. average of 36%. High college attainment predicts Democratic voting, and San Marcos sits in the top quarter (about 38%, above 85% of cities). A high never-married share predicts Democratic voting, and about 56% of adults in San Marcos have never been married, in the top fraction of cities.

Walkability and Democratic lean

Places with a highly walkable street grid tend to lean Democratic; San Marcos, TX sits in the top quarter nationally on this measure. A walkable street grid does not change how people vote; it mostly reflects how urban a place is.

Why turnout in San Marcos looks the way it does

Areas with limited routine healthcare access turn out at lower rates. San Marcos is in the bottom quarter nationally for routine-care measures such as insurance coverage, preventive screenings, and dental visits. The uninsured rate here is about 20%, about 10 points above the U.S. average of 10%. Renters vote less often than owners, and about 63% of households in San Marcos rent, compared to around 25% in nearby cities. Learn more about the findings and methodology on the political spectrum map.

Sources and methodology

Precinct-level voting records used to fit the model come from Texas Secretary of State, Elections Division, 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.