90042 is a Democratic stronghold. About 75% of voters here vote Democratic and 25% Republican.
About 51% of adults in 90042 typically vote, below the U.S. average of about 62%. Among adults in 90042, ~38% vote Democratic, ~13% Republican, and ~49% don't vote. The map below shows estimated turnout by block group.
How 90042 compares
Among zip codes within 15 miles, 90042 leans more Democratic than 103 of 145 neighbors.
90042 runs about 31 points more Democratic than California as a whole.
Politics vary noticeably by block within 90042. The west side is the most Democratic-leaning (D+55) and the southeast side is the least Democratic-leaning (D+40), a spread of about 15 points.
Why 90042 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 90042, not a ranked or complete list of what matters most.
Dense areas vote Democratic. More than 99% of residents in 90042 live in densely developed areas, about 63 points above the U.S. average of 36%. High college attainment predicts Democratic voting, and 90042 sits in the top quarter (about 42%, above 83% of zip codes). A high never-married share predicts Democratic voting, and about 43% of adults in 90042 have never been married, above 91% of zip codes.
Paved land cover and Democratic lean
Places with extensive paved surfaces tend to lean Democratic; 90042, CA sits in the top tenth 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 90042 looks the way it does
Areas with limited routine healthcare access turn out at lower rates. 90042 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 53% of households in 90042 rent, about 28 points above the U.S. average of 25%. Crowded housing lines up with lower turnout, and about 10% of homes in 90042 have more than one occupant per room, above 96% 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.