Marshall County leans heavily Republican by roughly 36 points: about 32% of voters vote Democratic and 68% Republican.
About 83% of adults in Marshall County typically vote, above the U.S. average of about 62%. Among adults in Marshall County, ~27% vote Democratic, ~56% Republican, and ~17% don't vote. The map below shows estimated turnout by block group.
How Marshall County compares
Among counties within 50 miles, Marshall County leans more Republican than 7 of 10 neighbors.
Marshall County runs about 48 points more Republican than Illinois as a whole. Illinois leans Democratic overall, while Marshall County is one of the few Republican-leaning pockets.
Politics vary noticeably by city within Marshall County. The northwest side is the most Republican-leaning (R+47) and the north side is the least Republican-leaning (R+32), a spread of about 15 points.
Why Marshall 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 Marshall County, not a ranked or complete list of what matters most.
Car-dependent areas vote Republican. About 87% of residents in Marshall County drive to work alone, about 13 points above the U.S. average of 74%. A high white share with below-average college attainment predicts Republican voting, and Marshall County fits that profile on both counts. Marshall 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; Marshall County, IL sits below the national average on this measure.
Why turnout in Marshall County looks the way it does
Turnout in Marshall 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
- Putnam County, IL R+28
- Woodford County, IL R+40
- Bureau County, IL R+27
- Stark County, IL R+47
- Peoria County, IL D+14
- LaSalle County, IL R+21
- Tazewell County, IL R+29
- Livingston County, IL R+38
- McLean County, IL D+5
- Henry County, IL R+24
Counties with Similar Populations
- Valley County, ID R+41
- Shelby County, IA R+48
- Juab County, UT R+71
- Marion County, KS R+52
- Cherokee County, IA R+42
- Terry County, TX R+49
- Northumberland County, VA R+19
- Ward County, TX R+56
- Magoffin County, KY R+67
- Barton County, MO R+65
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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.