91748 leans slightly Democratic by roughly 10 points: about 55% of voters vote Democratic and 45% Republican.
About 50% of adults in 91748 typically vote, below the U.S. average of about 62%. Among adults in 91748, ~27% vote Democratic, ~23% Republican, and ~50% don't vote. The map below shows estimated turnout by block group.
How 91748 compares
Among zip codes within 15 miles, 91748 leans more Democratic than 33 of 89 neighbors.
91748 runs about 10 points more Republican than California as a whole.
Politics vary noticeably by block within 91748. The west side is the most Democratic-leaning (D+16) and the southeast side is the least Democratic-leaning (D+3), a spread of about 13 points.
Why 91748 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 91748, not a ranked or complete list of what matters most.
Dense areas vote Democratic. About 89% of residents in 91748 live in densely developed areas, about 52 points above the U.S. average of 36%. High college attainment predicts Democratic voting, and 91748 sits in the top quarter (about 35%, above 75% of zip codes).
Walkability and Democratic lean
Places with a highly walkable street grid tend to lean Democratic; 91748, 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 91748 looks the way it does
Crowded housing lines up with lower turnout. About 8% of homes in 91748 have more than one occupant per room, above 94% of zip codes. Renters vote less often than owners, and about 34% of households in 91748 rent, above 80% 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.