Harris County leans slightly Democratic by roughly 12 points: about 56% of voters vote Democratic and 44% Republican.
About 49% of adults in Harris County typically vote, below the U.S. average of about 62%. Among adults in Harris County, ~27% vote Democratic, ~22% Republican, and ~51% don't vote. The map below shows estimated turnout by block group.
How Harris County compares
Among counties within 50 miles, Harris County is the most Democratic-leaning.
Harris County runs about 27 points more Democratic than Texas as a whole. Texas leans Republican overall, while Harris County is one of the few Democratic-leaning pockets.
Politics vary noticeably by city within Harris County. The south side runs the most Democratic (D+49) and the northwest side runs the most Republican (R+3), a spread of about 52 points.
Why Harris County leans the way it does
This analysis examined 14,881 data points per county to find what predicts political lean and turnout. The items below are a few correlations that stood out for Harris County, not a ranked or complete list of what matters most.
Dense areas vote Democratic. About 93% of residents in Harris County live in densely developed areas, about 57 points above the U.S. average of 36%. High college attainment predicts Democratic voting, and Harris County sits in the top quarter (about 32%, above 81% of counties). A high never-married share predicts Democratic voting, and about 38% of adults in Harris County have never been married, above 91% of counties.
Walkability and Democratic lean
Places with a highly walkable street grid tend to lean Democratic; Harris County, TX sits in the top tenth 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 Harris County looks the way it does
Areas with limited routine healthcare access turn out at lower rates. Harris County 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 23%, about 12 points above the U.S. average of 10%. Renters vote less often than owners, and about 42% of households in Harris County rent, compared to around 23% in nearby counties. Learn more about the findings and methodology on the political spectrum map.
Nearby Counties
- Fort Bend County, TX D+6
- Montgomery County, TX R+35
- Brazoria County, TX R+17
- Waller County, TX R+20
- Galveston County, TX R+13
- Liberty County, TX R+50
- Chambers County, TX R+58
- Austin County, TX R+54
- San Jacinto County, TX R+57
- Grimes County, TX R+42
Counties with Similar Populations
- Maricopa County, AZ D+3
- Cook County, IL D+42
- San Diego County, CA D+17
- Orange County, CA D+6
- Kings County, NY D+34
- Miami-Dade County, FL R+8
- Dallas County, TX D+27
- Riverside County, CA Even
- Queens County, NY D+23
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.