St. Charles leans slightly Republican by roughly 6 points: about 47% of voters vote Democratic and 53% Republican.
About 73% of adults in St. Charles typically vote, above the U.S. average of about 62%. Among adults in St. Charles, ~34% vote Democratic, ~39% Republican, and ~27% don't vote. The map below shows estimated turnout by block group.
How St. Charles compares
Among cities within 25 miles, St. Charles leans more Republican than 93 of 162 neighbors.
St. Charles runs about 13 points more Democratic than Missouri as a whole.
Politics vary noticeably by neighborhood within St. Charles. The southeast side runs the most Democratic (D+9) and the southwest side runs the most Republican (R+12), a spread of about 21 points.
Why St. Charles 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 St. Charles, not a ranked or complete list of what matters most.
St. Charles votes Republican even though it is densely developed (about 88%, far above the Missouri average of 22%). State and regional patterns outweigh the Democratic lean that density usually predicts here.
Population density and Democratic lean
Places with high population density tend to lean Democratic; St. Charles, MO sits in the top tenth nationally on this measure.
Why turnout in St. Charles looks the way it does
Areas with high high-school completion turn out at higher rates. About 96% of adults in St. Charles have completed high school, about 6 points above the Missouri average of 89%. Learn more about the findings and methodology on the political spectrum map.
Nearby Cities
- St. Peters, MO R+9
- Kampville, MO R+43
- Maryland Heights, MO D+27
- Cottleville, MO R+16
- Bridgeton, MO D+16
- Weldon Spring, MO R+23
- South Shore, MO R+54
- Chesterfield, MO D+5
Cities with Similar Populations
- Boulder, CO D+69
- Palm Bay, FL R+10
- Bellingham, WA D+49
- Keller, TX R+20
- Newark, DE D+34
- Rialto, CA D+20
- Spring Hill, FL R+28
- Saginaw, MI D+18
- Bethlehem, PA D+16
- Yakima, WA R+4
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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.