78666 leans Democratic by roughly 18 points: about 59% of voters vote Democratic and 41% Republican.
About 48% of adults in 78666 typically vote, below the U.S. average of about 62%. Among adults in 78666, ~28% vote Democratic, ~20% Republican, and ~52% don't vote. The map below shows estimated turnout by block group.
How 78666 compares
Among zip codes within 15 miles, 78666 is the most Democratic-leaning.
78666 runs about 31 points more Democratic than Texas as a whole. Texas leans Republican overall, while 78666 is one of the few Democratic-leaning pockets.
Politics vary noticeably by block within 78666. The north side runs the most Democratic (D+41) and the southwest side runs the most Republican (R+6), a spread of about 46 points.
Why 78666 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 78666, not a ranked or complete list of what matters most.
Areas with many never-married adults vote Democratic. About 55% of adults in 78666 have never been married, modestly above similar-sized zip codes (around 41%). High college attainment predicts Democratic voting, and 78666 sits in the top quarter (about 38%, above 79% of zip codes). 78666 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; 78666, TX sits in the top quarter nationally on this measure.
Why turnout in 78666 looks the way it does
Areas with limited routine healthcare access turn out at lower rates. 78666 is in the bottom quarter nationally for routine-care measures such as insurance coverage, preventive screenings, and dental visits. The uninsured rate here is about 20%, about 10 points above the U.S. average of 10%. Renters vote less often than owners, and about 61% of households in 78666 rent, compared to around 20% in nearby 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.