Carroll County leans heavily Republican by roughly 34 points: about 33% of voters vote Democratic and 67% Republican.
About 72% of adults in Carroll County typically vote, above the U.S. average of about 62%. Among adults in Carroll County, ~24% vote Democratic, ~48% Republican, and ~28% don't vote. The map below shows estimated turnout by block group.
How Carroll County compares
Among counties within 50 miles, Carroll County leans more Republican than 11 of 12 neighbors.
Carroll County runs about 45 points more Republican than Illinois as a whole. Illinois leans Democratic overall, while Carroll County is one of the few Republican-leaning pockets.
Politics vary noticeably by city within Carroll County. The southeast side is the most Republican-leaning (R+45) and the west side is the least Republican-leaning (R+24), a spread of about 20 points.
Why Carroll 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 Carroll County, not a ranked or complete list of what matters most.
Carroll County votes against the grain of Illinois. Illinois leans Democratic overall, while Carroll County runs about 45 points more Republican.
Population density and Republican lean
Places with low population density tend to lean Republican; Carroll County, IL sits below the national average on this measure.
Why turnout in Carroll County looks the way it does
Turnout in Carroll 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
- Whiteside County, IL R+20
- Clinton County, IA R+21
- Stephenson County, IL R+14
- Jo Daviess County, IL R+18
- Jackson County, IA R+35
- Lee County, IL R+21
- Ogle County, IL R+28
- Lafayette County, WI R+31
- Scott County, IA D+5
- Green County, WI R+11
Counties with Similar Populations
- Mercer County, IL R+33
- Aitkin County, MN R+33
- Jefferson County, GA D+5
- Grand County, CO R+6
- Leon County, TX R+69
- Henry County, KY R+51
- Jefferson County, IA R+4
- Pemiscot County, MO R+30
- Nottoway County, VA R+9
- Osage County, KS R+49
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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.