91963 leans slightly Republican by roughly 14 points: about 43% of voters vote Democratic and 57% Republican.
About 45% of adults in 91963 typically vote, below the U.S. average of about 62%. Among adults in 91963, ~19% vote Democratic, ~26% Republican, and ~55% don't vote. The map below shows estimated turnout by block group.
How 91963 compares
Among zip codes within 15 miles, 91963 leans more Republican than 1 of 4 neighbors.
91963 runs about 35 points more Republican than California as a whole. California leans Democratic overall, while 91963 is one of the few Republican-leaning pockets.
Why 91963 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 91963, not a ranked or complete list of what matters most.
Rural areas vote Republican. About 1% of residents in 91963 live in densely developed areas, about 56 points below the California average of 58%. A high family-household share predicts Republican voting, and about 81% of households in 91963 are family households, above 93% of zip codes. 91963 runs against the grain of California, a Republican-leaning pocket in a Democratic-leaning state.
Preventive-care access and voter turnout
Places with limited routine preventive-care access tend to turn out at a lower rate; 91963, CA sits in the bottom quarter nationally on this measure. Dental visits do not drive turnout; the rate reflects income, insurance, and healthcare access, which line up with who votes.
Why turnout in 91963 looks the way it does
Areas with limited routine healthcare access turn out at lower rates. 91963 is in the bottom quarter nationally for routine-care measures such as insurance coverage, preventive screenings, and dental visits. Renters vote less often than owners, and about 58% of households in 91963 rent, compared to around 25% in nearby zip codes. High food insecurity lines up with lower turnout, and about 22% of adults in 91963 report food insecurity, 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.