91784 leans slightly Republican by roughly 10 points: about 45% of voters vote Democratic and 55% Republican.
About 78% of adults in 91784 typically vote, above the U.S. average of about 62%. Among adults in 91784, ~35% vote Democratic, ~43% Republican, and ~22% don't vote. The map below shows estimated turnout by block group.
How 91784 compares
Among zip codes within 15 miles, 91784 leans more Republican than 32 of 35 neighbors.
91784 runs about 31 points more Republican than California as a whole. California leans Democratic overall, while 91784 is one of the few Republican-leaning pockets.
Politics vary noticeably by block within 91784. The northeast side is the most Republican-leaning (R+20) and the west side is the least Republican-leaning (R+4), a spread of about 15 points.
Why 91784 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 91784, not a ranked or complete list of what matters most.
91784 votes Republican even though it is densely developed (about 90%, far above the California average of 58%). State and regional patterns outweigh the Democratic lean that density usually predicts here. A high family-household share predicts Republican voting, and about 82% of households in 91784 are family households, above 95% of zip codes. 91784 runs against the grain of California, a Republican-leaning pocket in a Democratic-leaning state.
Food insecurity and voter turnout
Places with low food insecurity tend to turn out at a higher rate; 91784, CA sits in the bottom quarter nationally on this measure. Food insecurity does not directly drive turnout; it reflects economic hardship, which lines up with lower voting.
Why turnout in 91784 looks the way it does
Areas with strong routine healthcare access turn out at higher rates. 91784 is in the top quarter nationally for routine-care measures such as insurance coverage, preventive screenings, and dental visits. The dental-visit rate here is about 70%, about 10 points above the U.S. average of 60%. 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.