Decatur leans slightly Democratic by roughly 6 points: about 53% of voters vote Democratic and 47% Republican.
About 66% of adults in Decatur typically vote, near the U.S. average of about 62%. Among adults in Decatur, ~35% vote Democratic, ~31% Republican, and ~34% don't vote. The map below shows estimated turnout by block group.
How Decatur compares
Among cities within 25 miles, Decatur is the most Democratic-leaning.
Decatur runs about 6 points more Republican than Illinois as a whole.
Politics vary noticeably by neighborhood within Decatur. The west side runs the most Democratic (D+17) and the southeast side runs the most Republican (R+20), a spread of about 37 points.
Why Decatur 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 Decatur, not a ranked or complete list of what matters most.
Dense areas vote Democratic. About 79% of residents in Decatur live in densely developed areas, about 43 points above the U.S. average of 36%. A high never-married share predicts Democratic voting, and about 39% of adults in Decatur have never been married, above 93% of cities.
Paved land cover and Democratic lean
Places with extensive paved surfaces tend to lean Democratic; Decatur, IL sits in the top tenth nationally on this measure. Paved ground does not change how people vote; it mostly reflects how urban and built-up a place is.
Why turnout in Decatur looks the way it does
Turnout in Decatur 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
- Elwin, IL R+51
- Forsyth, IL R+33
- Long Creek, IL R+45
- Harristown, IL R+52
- Mount Zion, IL R+40
- Oreana, IL R+45
- Boody, IL R+54
- Warrensburg, IL R+56
- Oakley, IL R+53
- Argenta, IL R+45
Cities with Similar Populations
- Florissant, MO D+51
- Noblesville, IN R+15
- Dothan, AL R+17
- Redmond, WA D+45
- Tulare, CA R+16
- Queen Creek, AZ R+33
- Warwick, RI D+8
- Layton, UT R+23
- Charleston, WV R+5
- Plant City, FL R+26
All Local Stats
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Sources and methodology
Precinct-level voting records used to fit the model come from Illinois State Board 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.