78221 leans Democratic by roughly 18 points: about 59% of voters vote Democratic and 41% Republican.
About 40% of adults in 78221 typically vote, below the U.S. average of about 62%. Among adults in 78221, ~24% vote Democratic, ~16% Republican, and ~60% don't vote. The map below shows estimated turnout by block group.
How 78221 compares
Among zip codes within 15 miles, 78221 leans more Democratic than 16 of 44 neighbors.
78221 runs about 33 points more Democratic than Texas as a whole. Texas leans Republican overall, while 78221 is one of the few Democratic-leaning pockets.
Politics vary noticeably by block within 78221. The north side is the most Democratic-leaning (D+30) and the southeast side is the least Democratic-leaning (D+5), a spread of about 25 points.
Why 78221 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 78221, not a ranked or complete list of what matters most.
Dense areas vote Democratic. About 78% of residents in 78221 live in densely developed areas, about 42 points above the U.S. average of 36%. A high never-married share predicts Democratic voting, and about 41% of adults in 78221 have never been married, above 88% of zip codes. 78221 runs against the grain of Texas, a Democratic-leaning pocket in a Republican-leaning state.
Walkability and Democratic lean
Places with a highly walkable street grid tend to lean Democratic; 78221, 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 78221 looks the way it does
Areas with limited routine healthcare access turn out at lower rates. 78221 is in the bottom quarter nationally for routine-care measures such as insurance coverage, preventive screenings, and dental visits. The dental-visit rate here is about 47%, about 6 points below the Texas average of 54%. Low high-school completion lines up with lower turnout, and about 78% of adults in 78221 have completed high school, below 93% of zip codes. 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.