Union County leans heavily Republican by roughly 48 points: about 26% of voters vote Democratic and 74% Republican.
About 73% of adults in Union County typically vote, above the U.S. average of about 62%. Among adults in Union County, ~19% vote Democratic, ~54% Republican, and ~27% don't vote. The map below shows estimated turnout by block group.
How Union County compares
Among counties within 50 miles, Union County leans more Republican than 10 of 18 neighbors.
Union County runs about 59 points more Republican than Illinois as a whole. Illinois leans Democratic overall, while Union County is one of the few Republican-leaning pockets.
Politics vary noticeably by city within Union County. The southeast side is the most Republican-leaning (R+57) and the north side is the least Republican-leaning (R+42), a spread of about 15 points.
Why Union 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 Union County, not a ranked or complete list of what matters most.
Union County votes against the grain of Illinois. Illinois leans Democratic overall, while Union County runs about 59 points more Republican.
Housing overcrowding and voter turnout
Places with low overcrowding tend to turn out at a higher rate; Union County, IL sits in the bottom tenth nationally on this measure.
Why turnout in Union County looks the way it does
Turnout in Union 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
- Pulaski County, IL R+26
- Jackson County, IL D+7
- Johnson County, IL R+41
- Cape Girardeau County, MO R+34
- Alexander County, IL R+4
- Williamson County, IL R+36
- Ballard County, KY R+62
- Massac County, IL R+46
- Scott County, MO R+43
- Franklin County, IL R+52
Counties with Similar Populations
- Cook County, GA R+34
- Bristol City, VA R+32
- Manassas Park City, VA D+19
- Sharp County, AR R+62
- Humboldt County, NV R+53
- Ben Hill County, GA R+17
- Park County, MT R+14
- Richland County, WI R+19
- Arkansas County, AR R+33
- Chester County, TN R+61
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.