78004 is a Republican stronghold. About 22% of voters here vote Democratic and 78% Republican.
About 91% of adults in 78004 typically vote, above the U.S. average of about 62%. Among adults in 78004, ~20% vote Democratic, ~71% Republican, and ~9% don't vote. The map below shows estimated turnout by block group.
How 78004 compares
Among zip codes within 15 miles, 78004 leans more Republican than 5 of 6 neighbors.
78004 runs about 43 points more Republican than Texas as a whole.
Why 78004 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 78004, not a ranked or complete list of what matters most.
Areas with many family households vote Republican. About 86% of households in 78004 are family households, about 19 points above the U.S. average of 67%.
High-school completion, developed land, and voter turnout
Places that combine high-school-completion-heavy adults and a rural land-use pattern tend to turn out at a higher rate, as 78004, TX does.
Why turnout in 78004 looks the way it does
Areas with strong routine healthcare access turn out at higher rates. 78004 is in the top quarter nationally for routine-care measures such as insurance coverage, preventive screenings, and dental visits. The dental-visit rate here is about 70%, about 10 points above the U.S. average of 60%. Homeowners vote more often than renters, and about 95% of households in 78004 own their home, about 20 points above the U.S. average of 75%. High high-school completion lines up with higher turnout, and about 99% of adults in 78004 have completed high school, above 98% 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.