Grand Detour leans heavily Republican by roughly 34 points: about 33% of voters vote Democratic and 67% Republican.
About 77% of adults in Grand Detour typically vote, above the U.S. average of about 62%. Among adults in Grand Detour, ~25% vote Democratic, ~52% Republican, and ~23% don't vote. The map below shows estimated turnout by block group.
How Grand Detour compares
Among cities within 25 miles, Grand Detour leans more Republican than 20 of 63 neighbors.
Grand Detour runs about 45 points more Republican than Illinois as a whole. Illinois leans Democratic overall, while Grand Detour is one of the few Republican-leaning pockets.
Why Grand Detour leans the way it does
This analysis examined 14,881 data points per city to find what predicts political lean and turnout. The items below are a few correlations that stood out for Grand Detour, not a ranked or complete list of what matters most.
Grand Detour votes against the grain of Illinois. Illinois leans Democratic overall, while Grand Detour runs about 45 points more Republican. Car-dependent areas vote Republican, and about 86% of residents in Grand Detour drive to work alone, above 84% of cities.
High-school completion and voter turnout
Places with high-school-completion-heavy adults tend to turn out at a higher rate; Grand Detour, IL sits in the top quarter nationally on this measure.
Why turnout in Grand Detour looks the way it does
Homeowners vote more often than renters. About 96% of households in Grand Detour own their home, about 16 points above the Illinois average of 80%. High high-school completion lines up with higher turnout, and about 97% of adults in Grand Detour have completed high school, above 90% of cities. Learn more about the findings and methodology on the political spectrum map.
Nearby Cities
- Dixon, IL R+13
- Kingdom, IL R+39
- Woosung, IL R+26
- Nachusa, IL R+36
- Stratford, IL R+37
- Prairieville, IL R+27
- Franklin Grove, IL R+30
- Oregon, IL R+24
- Honey Creek, IL R+34
- Mount Morris, IL R+25
Cities with Similar Populations
- New Bethel, TN R+64
- Menno, PA R+73
- Herbert Springs, MS R+85
- Pickens, TX R+70
- Leola, SD R+69
- Gilman City, MO R+72
- Paige, VA R+17
- Como, IL R+37
- McHue, AR R+67
- Terra Ceia, NC R+47
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.