90004 leans heavily Democratic by roughly 48 points: about 74% of voters vote Democratic and 26% Republican.
About 40% of adults in 90004 typically vote, below the U.S. average of about 62%. Among adults in 90004, ~30% vote Democratic, ~10% Republican, and ~60% don't vote. The map below shows estimated turnout by block group.
How 90004 compares
Among zip codes within 15 miles, 90004 leans more Democratic than 99 of 168 neighbors.
90004 runs about 27 points more Democratic than California as a whole.
Why 90004 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 90004, not a ranked or complete list of what matters most.
Dense areas vote Democratic. More than 99% of residents in 90004 live in densely developed areas, about 64 points above the U.S. average of 36%. High college attainment predicts Democratic voting, and 90004 sits in the top quarter (about 40%, above 81% of zip codes). A high never-married share predicts Democratic voting, and about 51% of adults in 90004 have never been married, above 95% of zip codes.
Population density and Democratic lean
Places with high population density tend to lean Democratic; 90004, CA sits in the top tenth nationally on this measure.
Why turnout in 90004 looks the way it does
Areas with limited routine healthcare access turn out at lower rates. 90004 is in the bottom quarter nationally for routine-care measures such as insurance coverage, preventive screenings, and dental visits. Renters vote less often than owners, and about 84% of households in 90004 rent, about 59 points above the U.S. average of 25%. High food insecurity lines up with lower turnout, and about 25% of adults in 90004 report food insecurity, above 89% 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.