Affton leans slightly Democratic by roughly 10 points: about 55% of voters vote Democratic and 45% Republican.
About 76% of adults in Affton typically vote, above the U.S. average of about 62%. Among adults in Affton, ~42% vote Democratic, ~34% Republican, and ~24% don't vote. The map below shows estimated turnout by block group.
How Affton compares
Among cities within 25 miles, Affton leans more Democratic than 91 of 171 neighbors.
Affton runs about 29 points more Democratic than Missouri as a whole. Missouri leans Republican overall, while Affton is one of the few Democratic-leaning pockets.
Politics vary noticeably by neighborhood within Affton. The northwest side is the most Democratic-leaning (D+17) and the southwest side is the least Democratic-leaning (D+5), a spread of about 12 points.
Why Affton 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 Affton, not a ranked or complete list of what matters most.
Dense areas vote Democratic. About 99% of residents in Affton live in densely developed areas, about 62 points above the U.S. average of 36%. High college attainment predicts Democratic voting, and Affton sits in the top quarter (about 37%, above 85% of cities). Affton runs against the grain of Missouri, a Democratic-leaning pocket in a Republican-leaning state.
Population density and Democratic lean
Places with high population density tend to lean Democratic; Affton, MO sits in the top tenth nationally on this measure.
Why turnout in Affton looks the way it does
Turnout in Affton sits close to the national pattern. Routine healthcare access, homeownership, education, and food security all land near their national averages here. Learn more about the findings and methodology on the political spectrum map.
Nearby Cities
- Wilbur Park, MO D+11
- Lakeshire, MO Even
- St. George, MO D+10
- Grantwood Village, MO D+11
- Marlborough, MO D+20
- Green Park, MO D+5
- Bella Villa, MO D+6
- Shrewsbury, MO D+32
- Lemay, MO D+2
- Webster Groves, MO D+38
Cities with Similar Populations
- Cedar Mill, OR D+48
- Satellite Beach, FL R+24
- Cadillac, MI R+24
- Madisonville, LA R+49
- White Settlement, TX R+20
- Walnut Grove, WA D+11
- Marshfield, MA D+8
- Vinton, VA R+35
- Hot Springs Village, AR R+45
- Ripon, CA R+35
All Local Stats
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Sources and methodology
Precinct-level voting records used to fit the model come from Missouri 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.