78503 is a true toss-up. About 52% of voters here vote Democratic and 48% Republican.
About 46% of adults in 78503 typically vote, below the U.S. average of about 62%. Among adults in 78503, ~24% vote Democratic, ~22% Republican, and ~54% don't vote. The map below shows estimated turnout by block group.
How 78503 compares
Among zip codes within 15 miles, 78503 leans more Democratic than 13 of 14 neighbors.
78503 runs about 17 points more Democratic than Texas as a whole. Texas leans Republican overall, while 78503 is one of the few Democratic-leaning pockets.
Politics vary noticeably by block within 78503. The north side runs the most Democratic (D+10) and the southeast side runs the most Republican (R+11), a spread of about 22 points.
Why 78503 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 78503, not a ranked or complete list of what matters most.
78503 votes against the grain of Texas. Texas leans Republican overall, while 78503 runs about 17 points more Democratic.
Paved land cover and Democratic lean
Places with extensive paved surfaces tend to lean Democratic; 78503, TX sits in the top quarter 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 78503 looks the way it does
Areas with limited routine healthcare access turn out at lower rates. 78503 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 44%, about 10 points below the Texas average of 54%. Renters vote less often than owners, and about 38% of households in 78503 rent, above 85% of zip codes. Low high-school completion lines up with lower turnout, and about 72% of adults in 78503 have completed high school, below 97% 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.