91789 leans slightly Democratic by roughly 10 points: about 55% of voters vote Democratic and 45% Republican.
About 64% of adults in 91789 typically vote, near the U.S. average of about 62%. Among adults in 91789, ~35% vote Democratic, ~29% Republican, and ~36% don't vote. The map below shows estimated turnout by block group.
How 91789 compares
Among zip codes within 15 miles, 91789 leans more Democratic than 26 of 72 neighbors.
91789 runs about 11 points more Republican than California as a whole.
Why 91789 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 91789, not a ranked or complete list of what matters most.
Areas with high college attainment vote Democratic. About 53% of adults in 91789 hold a bachelor's degree, about 25 points above the U.S. average of 28%. Dense areas vote Democratic, and 91789 sits in the top fifth on density (about 93%, above 89% of zip codes).
Walkability and Democratic lean
Places with a highly walkable street grid tend to lean Democratic; 91789, CA sits in the top quarter 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 91789 looks the way it does
Turnout in 91789 sits close to the national pattern. Routine healthcare access, homeownership, education, and food security all land near their national averages here. 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.