91104 leans heavily Democratic by roughly 48 points: about 74% of voters vote Democratic and 26% Republican.
About 61% of adults in 91104 typically vote, near the U.S. average of about 62%. Among adults in 91104, ~45% vote Democratic, ~16% Republican, and ~39% don't vote. The map below shows estimated turnout by block group.
How 91104 compares
Among zip codes within 15 miles, 91104 leans more Democratic than 81 of 110 neighbors.
91104 runs about 29 points more Democratic than California as a whole.
Politics vary noticeably by block within 91104. The northwest side is the most Democratic-leaning (D+55) and the northeast side is the least Democratic-leaning (D+35), a spread of about 20 points.
Why 91104 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 91104, not a ranked or complete list of what matters most.
Dense areas vote Democratic. More than 99% of residents in 91104 live in densely developed areas, about 64 points above the U.S. average of 36%. High college attainment predicts Democratic voting, and 91104 sits in the top quarter (about 49%, above 89% of zip codes). A high never-married share predicts Democratic voting, and about 39% of adults in 91104 have never been married, above 86% of zip codes.
Walkability and Democratic lean
Places with a highly walkable street grid tend to lean Democratic; 91104, CA sits in the top tenth nationally on this measure. A walkable street grid does not change how people vote; it mostly reflects how urban a place is.
Why turnout in 91104 looks the way it does
Renters vote less often than owners. About 46% of households in 91104 rent, about 21 points above the U.S. average of 25%. Crowded housing lines up with lower turnout, and about 7% of homes in 91104 have more than one occupant per room, above 91% of zip codes. Low high-school completion lines up with lower turnout, and about 86% of adults in 91104 have completed high school, below 76% 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.