91001 is a Democratic stronghold. About 80% of voters here vote Democratic and 20% Republican.
About 73% of adults in 91001 typically vote, above the U.S. average of about 62%. Among adults in 91001, ~58% vote Democratic, ~15% Republican, and ~27% don't vote. The map below shows estimated turnout by block group.
How 91001 compares
Among zip codes within 15 miles, 91001 leans more Democratic than 95 of 102 neighbors.
91001 runs about 39 points more Democratic than California as a whole.
Politics vary noticeably by block within 91001. The north side is the most Democratic-leaning (D+65) and the southeast side is the least Democratic-leaning (D+44), a spread of about 22 points.
Why 91001 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 91001, not a ranked or complete list of what matters most.
Areas with high college attainment vote Democratic. About 54% of adults in 91001 hold a bachelor's degree, about 26 points above the U.S. average of 28%. Dense areas vote Democratic, and 91001 sits in the top fifth on density (about 92%, above 89% of zip codes).
Preventive-care access and voter turnout
Places with strong routine preventive-care access tend to turn out at a higher rate; 91001, CA sits in the top 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 91001 looks the way it does
Areas with strong routine healthcare access turn out at higher rates. 91001 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.