Warren County leans Republican by roughly 22 points: about 39% of voters vote Democratic and 61% Republican.
About 72% of adults in Warren County typically vote, above the U.S. average of about 62%. Among adults in Warren County, ~28% vote Democratic, ~44% Republican, and ~28% don't vote. The map below shows estimated turnout by block group.
How Warren County compares
Among counties within 50 miles, Warren County leans more Republican than 6 of 15 neighbors.
Warren County runs about 33 points more Republican than Illinois as a whole. Illinois leans Democratic overall, while Warren County is one of the few Republican-leaning pockets.
Politics vary noticeably by city within Warren County. The east side is the most Republican-leaning (R+45) and the north side is the least Republican-leaning (R+12), a spread of about 32 points.
Why Warren 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 Warren County, not a ranked or complete list of what matters most.
Warren County votes against the grain of Illinois. Illinois leans Democratic overall, while Warren County runs about 33 points more Republican.
Paved land cover and Democratic lean
Places with extensive paved surfaces tend to lean Democratic; Warren County, IL sits above the national average 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 Warren County looks the way it does
Turnout in Warren 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
- Knox County, IL R+9
- Henderson County, IL R+41
- Mercer County, IL R+33
- Des Moines County, IA R+8
- McDonough County, IL R+11
- Fulton County, IL R+31
- Louisa County, IA R+37
- Henry County, IL R+24
- Rock Island County, IL D+12
- Hancock County, IL R+45
Counties with Similar Populations
- Cross County, AR R+41
- Marion County, AR R+56
- Buckingham County, VA R+23
- Union County, SD R+43
- Edgar County, IL R+50
- Piscataquis County, ME R+34
- Hardin County, IA R+40
- Rabun County, GA R+56
- Giles County, VA R+58
- McCreary County, KY R+70
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.