90621 leans Democratic by roughly 16 points: about 58% of voters vote Democratic and 42% Republican.
About 50% of adults in 90621 typically vote, below the U.S. average of about 62%. Among adults in 90621, ~29% vote Democratic, ~21% Republican, and ~50% don't vote. The map below shows estimated turnout by block group.
How 90621 compares
Among zip codes within 15 miles, 90621 leans more Democratic than 48 of 114 neighbors.
90621 runs about 5 points more Republican than California as a whole.
Politics vary noticeably by block within 90621. The southwest side is the most Democratic-leaning (D+21) and the northeast side is the least Democratic-leaning (D+6), a spread of about 15 points.
Why 90621 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 90621, not a ranked or complete list of what matters most.
Dense areas vote Democratic. More than 99% of residents in 90621 live in densely developed areas, about 64 points above the U.S. average of 36%. A high never-married share predicts Democratic voting, and about 41% of adults in 90621 have never been married, above 89% of zip codes.
Population density and Democratic lean
Places with high population density tend to lean Democratic; 90621, CA sits in the top tenth nationally on this measure.
Why turnout in 90621 looks the way it does
Renters vote less often than owners. About 64% of households in 90621 rent, about 39 points above the U.S. average of 25%. Limited routine healthcare access lines up with lower turnout, and 90621 sits in the bottom quarter on routine-care measures. High food insecurity lines up with lower turnout, and about 20% of adults in 90621 report food insecurity, above 80% of 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 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.