91506 leans heavily Democratic by roughly 32 points: about 66% of voters vote Democratic and 34% Republican.
About 70% of adults in 91506 typically vote, above the U.S. average of about 62%. Among adults in 91506, ~46% vote Democratic, ~24% Republican, and ~30% don't vote. The map below shows estimated turnout by block group.
How 91506 compares
Among zip codes within 15 miles, 91506 leans more Democratic than 48 of 143 neighbors.
91506 runs about 12 points more Democratic than California as a whole.
Politics vary noticeably by block within 91506. The southeast side is the most Democratic-leaning (D+44) and the west side is the least Democratic-leaning (D+22), a spread of about 22 points.
Why 91506 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 91506, not a ranked or complete list of what matters most.
Dense areas vote Democratic. More than 99% of residents in 91506 live in densely developed areas, about 64 points above the U.S. average of 36%. High college attainment predicts Democratic voting, and 91506 sits in the top quarter (about 48%, above 87% of zip codes). A high never-married share predicts Democratic voting, and about 37% of adults in 91506 have never been married, above 84% of zip codes.
Population density and Democratic lean
Places with high population density tend to lean Democratic; 91506, CA sits in the top tenth nationally on this measure.
Why turnout in 91506 looks the way it does
Areas with strong routine healthcare access turn out at higher rates. 91506 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 71%, about 11 points above the U.S. average of 60%. 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 California Secretary of State, Elections, 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.