Costa Mesa, CA Political Map | Democrat & Republican Areas in Costa Mesa

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

Costa Mesa leans slightly Democratic by roughly 8 points: about 54% of voters vote Democratic and 46% Republican.

 

About 58% of adults in Costa Mesa typically vote, near the U.S. average of about 62%. Among adults in Costa Mesa, ~31% vote Democratic, ~27% Republican, and ~42% don't vote. The map below shows estimated turnout by block group.

How Costa Mesa compares

Among cities within 25 miles, Costa Mesa leans more Democratic than 42 of 81 neighbors.

Costa Mesa runs about 12 points more Republican than California as a whole.

Politics vary noticeably by neighborhood within Costa Mesa. The southwest side runs the most Democratic (D+14) and the southeast side runs the most Republican (R+8), a spread of about 22 points.

Why Costa Mesa leans the way it does

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

Dense areas vote Democratic. More than 99% of residents in Costa Mesa live in densely developed areas, about 63 points above the U.S. average of 36%. High college attainment predicts Democratic voting, and Costa Mesa sits in the top quarter (about 44%, above 90% of cities). A high never-married share predicts Democratic voting, and about 43% of adults in Costa Mesa have never been married, above 95% of cities.

Population density and Democratic lean

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

Why turnout in Costa Mesa looks the way it does

Renters vote less often than owners. About 59% of households in Costa Mesa rent, about 35 points above the U.S. average of 25%. Crowded housing lines up with lower turnout, and about 10% of homes in Costa Mesa have more than one occupant per room, above 96% of cities. 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.