91977 leans Democratic by roughly 16 points: about 58% of voters vote Democratic and 42% Republican.
About 57% of adults in 91977 typically vote, near the U.S. average of about 62%. Among adults in 91977, ~33% vote Democratic, ~24% Republican, and ~43% don't vote. The map below shows estimated turnout by block group.
How 91977 compares
Among zip codes within 15 miles, 91977 leans more Democratic than 15 of 51 neighbors.
91977 runs about 4 points more Republican than California as a whole.
Politics vary noticeably by block within 91977. The west side is the most Democratic-leaning (D+21) and the east side is the least Democratic-leaning (D+9), a spread of about 12 points.
Why 91977 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 91977, not a ranked or complete list of what matters most.
Dense areas vote Democratic. About 93% of residents in 91977 live in densely developed areas, about 56 points above the U.S. average of 36%. A high never-married share predicts Democratic voting, and about 37% of adults in 91977 have never been married, above 83% of zip codes.
Paved land cover and Democratic lean
Places with extensive paved surfaces tend to lean Democratic; 91977, CA sits in the top quarter nationally on this measure. Paved ground does not change how people vote; it mostly reflects how urban and built-up a place is.
Why turnout in 91977 looks the way it does
Crowded housing lines up with lower turnout. About 9% of homes in 91977 have more than one occupant per room, above 95% of zip codes. Renters vote less often than owners, and about 36% of households in 91977 rent, above 83% 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.