Montgomery County leans heavily Republican by roughly 44 points: about 28% of voters vote Democratic and 72% Republican.
About 75% of adults in Montgomery County typically vote, above the U.S. average of about 62%. Among adults in Montgomery County, ~21% vote Democratic, ~54% Republican, and ~25% don't vote. The map below shows estimated turnout by block group.
How Montgomery County compares
Among counties within 50 miles, Montgomery County leans more Republican than 4 of 11 neighbors.
Montgomery County runs about 55 points more Republican than Illinois as a whole. Illinois leans Democratic overall, while Montgomery County is one of the few Republican-leaning pockets.
Politics vary noticeably by city within Montgomery County. The east side is the most Republican-leaning (R+58) and the south side is the least Republican-leaning (R+33), a spread of about 25 points.
Why Montgomery 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 Montgomery County, not a ranked or complete list of what matters most.
Montgomery County votes against the grain of Illinois. Illinois leans Democratic overall, while Montgomery County runs about 55 points more Republican. A high white share with below-average college attainment predicts Republican voting, and Montgomery County fits that profile on both counts.
Foreign-born share and voter turnout
Places with a low foreign-born share tend to turn out in mixed patterns; Montgomery County, IL sits in the bottom tenth nationally on this measure.
Why turnout in Montgomery County looks the way it does
Turnout in Montgomery 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
- Macoupin County, IL R+42
- Bond County, IL R+39
- Christian County, IL R+45
- Fayette County, IL R+59
- Madison County, IL R+11
- Shelby County, IL R+58
- Sangamon County, IL Even
- Clinton County, IL R+47
- Jersey County, IL R+44
- Greene County, IL R+56
Counties with Similar Populations
- Wythe County, VA R+57
- Dillon County, SC R+5
- Dunklin County, MO R+50
- Bradford County, FL R+50
- Carroll County, AR R+48
- Baker County, FL R+61
- Codington County, SD R+42
- Leflore County, MS D+53
- Jones County, GA R+41
- Copiah County, MS D+6
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.