61840 leans heavily Republican by roughly 42 points: about 29% of voters vote Democratic and 71% Republican.
About 85% of adults in 61840 typically vote, above the U.S. average of about 62%. Among adults in 61840, ~25% vote Democratic, ~60% Republican, and ~15% don't vote. The map below shows estimated turnout by block group.
How 61840 compares
Among zip codes within 15 miles, 61840 leans more Republican than 12 of 17 neighbors.
61840 runs about 52 points more Republican than Illinois as a whole. Illinois leans Democratic overall, while 61840 is one of the few Republican-leaning pockets.
Politics vary noticeably by block within 61840. The west side is the most Republican-leaning (R+50) and the southwest side is the least Republican-leaning (R+34), a spread of about 16 points.
Why 61840 leans the way it does
This analysis examined 14,881 data points per zip code to find what predicts political lean and turnout. The items below are a few correlations that stood out for 61840, not a ranked or complete list of what matters most.
61840 votes against the grain of Illinois. Illinois leans Democratic overall, while 61840 runs about 52 points more Republican. Car-dependent areas vote Republican, and about 84% of residents in 61840 drive to work alone, above 83% of zip codes. A high family-household share predicts Republican voting, and about 90% of households in 61840 are family households, in the top fraction of zip codes.
Homeownership and voter turnout
Places with homeowner-heavy households tend to turn out at a higher rate; 61840, IL sits in the top tenth nationally on this measure.
Why turnout in 61840 looks the way it does
Areas with strong routine healthcare access turn out at higher rates. 61840 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 71%, about 11 points above the U.S. average of 60%. Homeowners vote more often than renters, and about 96% of households in 61840 own their home, compared to around 77% in nearby zip codes. High high-school completion lines up with higher turnout, and about 99% of adults in 61840 have completed high school, above 98% of zip codes. Learn more about the findings and methodology on the political spectrum map.
Nearby Zip Codes
Zip Codes with Similar Populations
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.