New Castle County leans heavily Democratic by roughly 34 points: about 67% of voters vote Democratic and 33% Republican.
About 71% of adults in New Castle County typically vote, above the U.S. average of about 62%. Among adults in New Castle County, ~48% vote Democratic, ~23% Republican, and ~29% don't vote. The map below shows estimated turnout by block group.
How New Castle County compares
Among counties within 50 miles, New Castle County leans more Democratic than 14 of 15 neighbors.
New Castle County runs about 18 points more Democratic than Delaware as a whole.
Politics vary noticeably by city within New Castle County. The east side is the most Democratic-leaning (D+67) and the northwest side is the least Democratic-leaning (D+16), a spread of about 51 points.
Why New Castle 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 New Castle County, not a ranked or complete list of what matters most.
Dense areas vote Democratic. About 78% of residents in New Castle County live in densely developed areas, about 41 points above the U.S. average of 36%. High college attainment predicts Democratic voting, and New Castle County sits in the top quarter (about 40%, above 91% of counties). A high never-married share predicts Democratic voting, and about 37% of adults in New Castle County have never been married, above 89% of counties.
Walkability and Democratic lean
Places with a highly walkable street grid tend to lean Democratic; New Castle County, DE sits in the top tenth 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 New Castle County looks the way it does
Turnout in New Castle County 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 Counties
- Salem County, NJ R+12
- Cecil County, MD R+29
- Chester County, PA D+14
- Delaware County, PA D+27
- Gloucester County, NJ R+2
- Cumberland County, NJ D+7
- Philadelphia County, PA D+56
- Camden County, NJ D+30
- Harford County, MD R+4
- Kent County, MD Even
Counties with Similar Populations
- Union County, NJ D+26
- Delaware County, PA D+27
- Bristol County, MA Even
- Pasco County, FL R+24
- Dane County, WI D+48
- Jefferson County, CO D+18
- Douglas County, NE D+17
- Baltimore City, MD D+72
- Volusia County, FL R+17
- Anne Arundel County, MD D+17
Sources and methodology
Precinct-level voting records used to fit the model come from Delaware Department 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.