78617 leans Democratic by roughly 18 points: about 59% of voters vote Democratic and 41% Republican.
About 45% of adults in 78617 typically vote, below the U.S. average of about 62%. Among adults in 78617, ~27% vote Democratic, ~18% Republican, and ~55% don't vote. The map below shows estimated turnout by block group.
How 78617 compares
Among zip codes within 15 miles, 78617 leans more Democratic than 4 of 28 neighbors.
78617 runs about 33 points more Democratic than Texas as a whole. Texas leans Republican overall, while 78617 is one of the few Democratic-leaning pockets.
Politics vary noticeably by block within 78617. The northwest side is the most Democratic-leaning (D+39) and the northeast side is the least Democratic-leaning (Even), a spread of about 38 points.
Why 78617 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 78617, not a ranked or complete list of what matters most.
78617 votes against the grain of Texas. Texas leans Republican overall, while 78617 runs about 33 points more Democratic. A high never-married share predicts Democratic voting, and about 42% of adults in 78617 have never been married, above 89% of zip codes.
Cancer-screening access and voter turnout
Places with low colon-cancer-screening access tend to turn out at a lower rate; 78617, TX sits in the bottom tenth nationally on this measure. Cancer screening does not drive turnout; it reflects income, insurance, and healthcare access.
Why turnout in 78617 looks the way it does
Areas with limited routine healthcare access turn out at lower rates. 78617 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 7 points below the Texas average of 54%. 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.