94521 leans Democratic by roughly 28 points: about 64% of voters vote Democratic and 36% Republican.
About 69% of adults in 94521 typically vote, above the U.S. average of about 62%. Among adults in 94521, ~44% vote Democratic, ~25% Republican, and ~31% don't vote. The map below shows estimated turnout by block group.
How 94521 compares
Among zip codes within 15 miles, 94521 leans more Democratic than 10 of 30 neighbors.
94521 runs about 9 points more Democratic than California as a whole.
Politics vary noticeably by block within 94521. The west side is the most Democratic-leaning (D+39) and the northeast side is the least Democratic-leaning (D+14), a spread of about 25 points.
Why 94521 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 94521, not a ranked or complete list of what matters most.
Dense areas vote Democratic. About 91% of residents in 94521 live in densely developed areas, about 55 points above the U.S. average of 36%. High college attainment predicts Democratic voting, and 94521 sits in the top quarter (about 45%, above 85% of zip codes).
Preventive-care access and voter turnout
Places with strong routine preventive-care access tend to turn out at a higher rate; 94521, CA sits in the top quarter nationally on this measure. Dental visits do not drive turnout; the rate reflects income, insurance, and healthcare access, which line up with who votes.
Why turnout in 94521 looks the way it does
Areas with strong routine healthcare access turn out at higher rates. 94521 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.