Monroe County leans heavily Republican by roughly 40 points: about 30% of voters vote Democratic and 70% Republican.
About 93% of adults in Monroe County typically vote, above the U.S. average of about 62%. Among adults in Monroe County, ~28% vote Democratic, ~65% Republican, and ~7% don't vote. The map below shows estimated turnout by block group.
How Monroe County compares
Among counties within 50 miles, Monroe County leans more Republican than 5 of 15 neighbors.
Monroe County runs about 50 points more Republican than Illinois as a whole. Illinois leans Democratic overall, while Monroe County is one of the few Republican-leaning pockets.
Politics vary noticeably by city within Monroe County. The southwest side is the most Republican-leaning (R+54) and the north side is the least Republican-leaning (R+29), a spread of about 25 points.
Why Monroe 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 Monroe County, not a ranked or complete list of what matters most.
Monroe County votes against the grain of Illinois. Illinois leans Democratic overall, while Monroe County runs about 50 points more Republican. A high family-household share predicts Republican voting, and about 72% of households in Monroe County are family households, above 87% of counties.
Preventive-care access and voter turnout
Places with strong routine preventive-care access tend to turn out at a higher rate; Monroe County, IL sits in the top tenth nationally on this measure. Dental visits do not drive turnout; the rate reflects income, insurance, and healthcare access, which line up with who votes.
Why turnout in Monroe County looks the way it does
Areas with strong routine healthcare access turn out at higher rates. Monroe County is in the top quarter nationally for routine-care measures such as insurance coverage, preventive screenings, and dental visits. The dental-visit rate here is about 69%, about 9 points above the U.S. average of 60%. Homeowners vote more often than renters, and about 85% of households in Monroe County own their home, above 96% of counties. High high-school completion lines up with higher turnout, and about 96% of adults in Monroe County have completed high school, above 96% of counties. Learn more about the findings and methodology on the political spectrum map.
Nearby Counties
- St. Clair County, IL D+13
- Jefferson County, MO R+39
- St. Louis City, MO D+65
- St. Louis County, MO D+28
- Randolph County, IL R+45
- Ste. Genevieve County, MO R+55
- Madison County, IL R+11
- St. Charles County, MO R+14
- Clinton County, IL R+47
- St. Francois County, MO R+48
Counties with Similar Populations
- Morrow County, OH R+58
- Lincoln County, MS R+37
- Howard County, TX R+50
- Silver Bow County, MT Even
- Wasatch County, UT R+33
- Chambers County, AL R+13
- Becker County, MN R+33
- Alcorn County, MS R+59
- Lincoln County, ME Even
- Lincoln County, NE R+46
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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.