78721 is a Democratic stronghold. About 83% of voters here vote Democratic and 17% Republican.
About 57% of adults in 78721 typically vote, near the U.S. average of about 62%. Among adults in 78721, ~47% vote Democratic, ~10% Republican, and ~43% don't vote. The map below shows estimated turnout by block group.
How 78721 compares
Among zip codes within 15 miles, 78721 leans more Democratic than 40 of 43 neighbors.
78721 runs about 80 points more Democratic than Texas as a whole. Texas leans Republican overall, while 78721 is one of the few Democratic-leaning pockets.
Why 78721 leans the way it does
This analysis examined 14,881 data points per zip code to find what predicts political lean and turnout. The items below are a few correlations that stood out for 78721, not a ranked or complete list of what matters most.
Dense areas vote Democratic. About 93% of residents in 78721 live in densely developed areas, about 56 points above the U.S. average of 36%. High college attainment predicts Democratic voting, and 78721 sits in the top quarter (about 49%, above 88% of zip codes). 78721 runs against the grain of Texas, a Democratic-leaning pocket in a Republican-leaning state.
Population density and Democratic lean
Places with high population density tend to lean Democratic; 78721, TX sits in the top quarter nationally on this measure.
Why turnout in 78721 looks the way it does
Areas with limited routine healthcare access turn out at lower rates. 78721 is in the bottom quarter nationally for routine-care measures such as insurance coverage, preventive screenings, and dental visits. Renters vote less often than owners, and about 45% of households in 78721 rent, compared to around 67% in nearby zip codes. High-crime urban areas turn out at lower rates, and 78721 sits in the top 15% on a violent-crime measure. Learn more about the findings and methodology on the political spectrum map.
Nearby Zip Codes
Zip Codes with Similar Populations
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.