Alameda County, CA Political Map | Democrat & Republican Areas in Alameda County

By the BestNeighborhood data science team. Last updated May 2026.

Alameda County leans heavily Democratic by roughly 48 points: about 74% of voters vote Democratic and 26% Republican.

 

About 55% of adults in Alameda County typically vote, below the U.S. average of about 62%. Among adults in Alameda County, ~41% vote Democratic, ~14% Republican, and ~45% don't vote. The map below shows estimated turnout by block group.

How Alameda County compares

Among counties within 50 miles, Alameda County leans more Democratic than 7 of 8 neighbors.

Alameda County runs about 29 points more Democratic than California as a whole.

Politics vary noticeably by city within Alameda County. The northwest side runs the most Democratic (D+73) and the northeast side runs the most Republican (R+12), a spread of about 85 points.

Why Alameda County leans the way it does

This analysis examined 14,881 data points per county to find what predicts political lean and turnout. The items below are a few correlations that stood out for Alameda County, not a ranked or complete list of what matters most.

Dense areas vote Democratic. About 93% of residents in Alameda County live in densely developed areas, about 56 points above the U.S. average of 36%. High college attainment predicts Democratic voting, and Alameda County sits in the top quarter (about 52%, above 98% of counties). A high never-married share predicts Democratic voting, and about 37% of adults in Alameda County have never been married, above 89% of counties.

Population density and Democratic lean

Places with high population density tend to lean Democratic; Alameda County, CA sits in the top tenth nationally on this measure.

Why turnout in Alameda County looks the way it does

Renters vote less often than owners. About 44% of households in Alameda County rent, about 19 points above the U.S. average of 25%. Crowded housing lines up with lower turnout, and about 8% of homes in Alameda County have more than one occupant per room, above 97% of counties. Learn more about the findings and methodology on the political spectrum map.

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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.