Hamilton County is a Republican stronghold. About 19% of voters here vote Democratic and 81% Republican.
About 82% of adults in Hamilton County typically vote, above the U.S. average of about 62%. Among adults in Hamilton County, ~16% vote Democratic, ~66% Republican, and ~18% don't vote. The map below shows estimated turnout by block group.
How Hamilton County compares
Among counties within 50 miles, Hamilton County leans more Republican than 16 of 19 neighbors.
Hamilton County runs about 73 points more Republican than Illinois as a whole. Illinois leans Democratic overall, while Hamilton County is one of the few Republican-leaning pockets.
Why Hamilton 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 Hamilton County, not a ranked or complete list of what matters most.
Car-dependent areas vote Republican. About 89% of residents in Hamilton County drive to work alone, about 15 points above the U.S. average of 74%. Hamilton County runs against the grain of Illinois, a Republican-leaning pocket in a Democratic-leaning state.
Population density and Republican lean
Places with low population density tend to lean Republican; Hamilton County, IL sits below the national average on this measure.
Why turnout in Hamilton County looks the way it does
Turnout in Hamilton County sits close to the national pattern. Learn more about the findings and methodology on the political spectrum map.
Nearby Counties
- White County, IL R+59
- Wayne County, IL R+65
- Franklin County, IL R+52
- Saline County, IL R+50
- Jefferson County, IL R+44
- Gallatin County, IL R+60
- Williamson County, IL R+36
- Edwards County, IL R+64
- Posey County, IN R+45
- Perry County, IL R+49
Counties with Similar Populations
- Traill County, ND R+37
- Liberty County, FL R+45
- Lemhi County, ID R+61
- Twiggs County, GA R+22
- Graham County, NC R+62
- Allendale County, SC D+37
- Schoolcraft County, MI R+28
- Clay County, WV R+63
- Thomas County, KS R+67
- San Augustine County, TX R+47
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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.