91602 leans heavily Democratic by roughly 48 points: about 74% of voters vote Democratic and 26% Republican.
About 63% of adults in 91602 typically vote, near the U.S. average of about 62%. Among adults in 91602, ~47% vote Democratic, ~16% Republican, and ~37% don't vote. The map below shows estimated turnout by block group.
How 91602 compares
Among zip codes within 15 miles, 91602 leans more Democratic than 88 of 150 neighbors.
91602 runs about 27 points more Democratic than California as a whole.
Politics vary noticeably by block within 91602. The north side is the most Democratic-leaning (D+55) and the northeast side is the least Democratic-leaning (D+37), a spread of about 18 points.
Why 91602 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 91602, not a ranked or complete list of what matters most.
Dense areas vote Democratic. More than 99% of residents in 91602 live in densely developed areas, about 64 points above the U.S. average of 36%. High college attainment predicts Democratic voting, and 91602 sits in the top quarter (about 55%, above 92% of zip codes). A high never-married share predicts Democratic voting, and about 48% of adults in 91602 have never been married, above 94% of zip codes.
Population density and Democratic lean
Places with high population density tend to lean Democratic; 91602, CA sits in the top tenth nationally on this measure.
Why turnout in 91602 looks the way it does
Areas with strong routine healthcare access turn out at higher rates. 91602 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%. 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.