Mill Valley, CA Political Map | Democrat & Republican Areas in Mill Valley

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

Mill Valley is a Democratic stronghold. About 77% of voters here vote Democratic and 23% Republican.

 

About 80% of adults in Mill Valley typically vote, above the U.S. average of about 62%. Among adults in Mill Valley, ~62% vote Democratic, ~18% Republican, and ~20% don't vote. The map below shows estimated turnout by block group.

How Mill Valley compares

Among cities within 25 miles, Mill Valley leans more Democratic than 53 of 73 neighbors.

Mill Valley runs about 34 points more Democratic than California as a whole.

Politics vary noticeably by neighborhood within Mill Valley. The northwest side is the most Democratic-leaning (D+62) and the southeast side is the least Democratic-leaning (D+44), a spread of about 18 points.

Why Mill Valley 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 Mill Valley, not a ranked or complete list of what matters most.

Areas with high college attainment vote Democratic. About 74% of adults in Mill Valley hold a bachelor's degree, about 46 points above the U.S. average of 28%. Dense areas vote Democratic, and Mill Valley sits in the top fifth on density (about 75%, above 93% of cities). A high never-married share predicts Democratic voting, and about 31% of adults in Mill Valley have never been married, above 78% of cities.

Population density and Democratic lean

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

Why turnout in Mill Valley looks the way it does

Areas with strong routine healthcare access turn out at higher rates. Mill Valley 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 76%, about 16 points above the U.S. average of 60%. High high-school completion lines up with higher turnout, and about 98% of adults in Mill Valley have completed high school, above 97% 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.