Chester County leans slightly Democratic by roughly 14 points: about 57% of voters vote Democratic and 43% Republican.
About 87% of adults in Chester County typically vote, above the U.S. average of about 62%. Among adults in Chester County, ~50% vote Democratic, ~38% Republican, and ~12% don't vote. The map below shows estimated turnout by block group.
How Chester County compares
Among counties within 50 miles, Chester County leans more Democratic than 10 of 16 neighbors.
Chester County runs about 15 points more Democratic than Pennsylvania as a whole. Pennsylvania is roughly evenly split, and Chester County sits clearly on the Democratic side.
Politics vary noticeably by city within Chester County. The northeast side runs the most Democratic (D+25) and the northwest side runs the most Republican (R+19), a spread of about 44 points.
Why Chester 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 Chester County, not a ranked or complete list of what matters most.
Areas with high college attainment vote Democratic. About 57% of adults in Chester County hold a bachelor's degree, about 28 points above the U.S. average of 28%. Dense areas vote Democratic, and Chester County sits in the top fifth on density (about 60%, above 85% of counties). Chester County runs against the grain of Pennsylvania, a Democratic-leaning outlier in a roughly evenly split state.
Walkability and Democratic lean
Places with a highly walkable street grid tend to lean Democratic; Chester County, PA sits in the top quarter nationally on this measure. A walkable street grid does not change how people vote; it mostly reflects how urban a place is.
Why turnout in Chester County looks the way it does
Areas with strong routine healthcare access turn out at higher rates. Chester County 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 71%, about 11 points above the U.S. average of 60%. High high-school completion lines up with higher turnout, and about 95% of adults in Chester County have completed high school, above 90% of counties. Learn more about the findings and methodology on the political spectrum map.
Nearby Counties
- Delaware County, PA D+27
- New Castle County, DE D+33
- Montgomery County, PA D+21
- Berks County, PA R+8
- Philadelphia County, PA D+56
- Cecil County, MD R+29
- Salem County, NJ R+12
- Lancaster County, PA R+17
- Gloucester County, NJ R+2
- Camden County, NJ D+30
Counties with Similar Populations
- Montgomery County, OH D+6
- Plymouth County, MA D+11
- Spokane County, WA R+3
- Summit County, OH D+10
- Guilford County, NC D+30
- Greenville County, SC R+14
- Passaic County, NJ D+4
- Sedgwick County, KS R+7
- Camden County, NJ D+30
- Adams County, CO D+11
Sources and methodology
Precinct-level voting records used to fit the model come from Pennsylvania Department of State, Bureau of 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.