Adams County leans heavily Republican by roughly 40 points: about 30% of voters vote Democratic and 70% Republican.
About 75% of adults in Adams County typically vote, above the U.S. average of about 62%. Among adults in Adams County, ~23% vote Democratic, ~52% Republican, and ~25% don't vote. The map below shows estimated turnout by block group.
How Adams County compares
Among counties within 50 miles, Adams County leans more Republican than 2 of 13 neighbors.
Adams County runs about 51 points more Republican than Illinois as a whole. Illinois leans Democratic overall, while Adams County is one of the few Republican-leaning pockets.
Politics vary noticeably by city within Adams County. The east side is the most Republican-leaning (R+74) and the west side is the least Republican-leaning (R+22), a spread of about 52 points.
Why Adams 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 Adams County, not a ranked or complete list of what matters most.
Adams County votes against the grain of Illinois. Illinois leans Democratic overall, while Adams County runs about 51 points more Republican. Dense places usually vote Democratic, but Adams County runs against that pattern.
High-school completion, uninsured rate, and voter turnout
Places that combine high-school-completion-heavy adults and a low uninsured rate tend to turn out at a higher rate, as Adams County, IL does.
Why turnout in Adams County looks the way it does
Areas with high high-school completion turn out at higher rates. About 94% of adults in Adams County have completed high school, above 83% of counties. Learn more about the findings and methodology on the political spectrum map.
Nearby Counties
- Marion County, MO R+44
- Lewis County, MO R+59
- Ralls County, MO R+62
- Brown County, IL R+39
- Pike County, IL R+57
- Hancock County, IL R+45
- Clark County, MO R+60
- Pike County, MO R+55
- Shelby County, MO R+65
- Schuyler County, IL R+44
Counties with Similar Populations
- Warren County, NY R+2
- Mason County, WA R+5
- Sauk County, WI R+20
- Tehama County, CA R+35
- Armstrong County, PA R+52
- Starr County, TX R+7
- Harrison County, WV R+41
- Wilkes County, NC R+57
- Marquette County, MI Even
- Apache County, AZ D+30
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.