91387 is a true toss-up. About 51% of voters here vote Democratic and 49% Republican.
About 54% of adults in 91387 typically vote, below the U.S. average of about 62%. Among adults in 91387, ~28% vote Democratic, ~27% Republican, and ~45% don't vote. The map below shows estimated turnout by block group.
How 91387 compares
Among zip codes within 15 miles, 91387 sits roughly in the middle of the political spectrum, with 5 neighbors leaning further in the place's direction and 20 leaning the other way.
91387 runs about 18 points more Republican than California as a whole.
Politics vary noticeably by block within 91387. The west side runs the most Democratic (D+22) and the east side runs the most Republican (R+25), a spread of about 47 points.
Why 91387 leans the way it does
Density, race composition, education, and family structure all sit close to their national averages in 91387. The lean here lands roughly where demographic data alone would predict.
Paved land cover and Democratic lean
Places with extensive paved surfaces tend to lean Democratic; 91387, 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 91387 looks the way it does
Crowded housing lines up with lower turnout. About 9% of homes in 91387 have more than one occupant per room, above 95% 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.