91801 leans Democratic by roughly 28 points: about 64% of voters vote Democratic and 36% Republican.
About 46% of adults in 91801 typically vote, below the U.S. average of about 62%. Among adults in 91801, ~29% vote Democratic, ~17% Republican, and ~54% don't vote. The map below shows estimated turnout by block group.
How 91801 compares
Among zip codes within 15 miles, 91801 leans more Democratic than 53 of 138 neighbors.
91801 runs about 8 points more Democratic than California as a whole.
Politics vary noticeably by block within 91801. The northwest side is the most Democratic-leaning (D+32) and the southeast side is the least Democratic-leaning (D+19), a spread of about 13 points.
Why 91801 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 91801, not a ranked or complete list of what matters most.
Dense areas vote Democratic. More than 99% of residents in 91801 live in densely developed areas, about 64 points above the U.S. average of 36%. High college attainment predicts Democratic voting, and 91801 sits in the top quarter (about 43%, above 83% of zip codes). A high never-married share predicts Democratic voting, and about 37% of adults in 91801 have never been married, above 83% of zip codes.
Population density and Democratic lean
Places with high population density tend to lean Democratic; 91801, CA sits in the top tenth nationally on this measure.
Why turnout in 91801 looks the way it does
Renters vote less often than owners. About 61% of households in 91801 rent, about 36 points above the U.S. average of 25%. Crowded housing lines up with lower turnout, and about 7% of homes in 91801 have more than one occupant per room, above 92% 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.