Oak Brook is a true toss-up. About 51% of voters here vote Democratic and 49% Republican.
About 78% of adults in Oak Brook typically vote, above the U.S. average of about 62%. Among adults in Oak Brook, ~40% vote Democratic, ~38% Republican, and ~22% don't vote. The map below shows estimated turnout by block group.
How Oak Brook compares
Among cities within 25 miles, Oak Brook sits roughly in the middle of the political spectrum, with 44 neighbors leaning further in the place's direction and 130 leaning the other way.
Oak Brook runs about 9 points more Republican than Illinois as a whole.
Politics vary noticeably by neighborhood within Oak Brook. The northwest side runs the most Democratic (D+29) and the southeast side runs the most Republican (R+5), a spread of about 33 points.
Why Oak Brook leans the way it does
Density, race composition, education, and family structure all sit close to their national averages in Oak Brook. The lean here lands roughly where demographic data alone would predict.
Preventive-care access and voter turnout
Places with strong routine preventive-care access tend to turn out at a higher rate; Oak Brook, 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 Oak Brook looks the way it does
Areas with strong routine healthcare access turn out at higher rates. Oak Brook 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 72%, about 12 points above the U.S. average of 60%. High high-school completion lines up with higher turnout, and about 96% of adults in Oak Brook have completed high school, above 86% of cities. Learn more about the findings and methodology on the political spectrum map.
Nearby Cities
- Oakbrook Terrace, IL D+15
- Clarendon Hills, IL D+14
- Westmont, IL D+16
- Villa Park, IL D+17
- Lombard, IL D+14
- Western Springs, IL D+21
- Hillside, IL D+53
- Elmhurst, IL D+18
- Westchester, IL D+34
- Hinsdale, IL D+12
Cities with Similar Populations
- Greenwell Springs, LA R+56
- Strawberry Plains, TN R+65
- Mendham, NJ Even
- Inwood, NY D+14
- Arizona City, AZ R+20
- Trinidad, CO R+4
- Middleton, MA R+4
- Collegedale, TN R+28
- Tell City, IN R+32
- Lebanon, NH D+45
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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.