Boulder Hill, IL Political Map | Democrat & Republican Areas in Boulder Hill

By the BestNeighborhood data science team. Last updated May 2026.

Boulder Hill leans slightly Democratic by roughly 8 points: about 54% of voters vote Democratic and 46% Republican.

 

About 62% of adults in Boulder Hill typically vote, near the U.S. average of about 62%. Among adults in Boulder Hill, ~33% vote Democratic, ~29% Republican, and ~38% don't vote. The map below shows estimated turnout by block group.

How Boulder Hill compares

Among cities within 25 miles, Boulder Hill leans more Democratic than 63 of 100 neighbors.

Politically, Boulder Hill sits close to the rest of Illinois.

Why Boulder Hill 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 Boulder Hill, not a ranked or complete list of what matters most.

Dense areas vote Democratic. About 96% of residents in Boulder Hill live in densely developed areas, about 60 points above the U.S. average of 36%. A high never-married share predicts Democratic voting, and about 33% of adults in Boulder Hill have never been married, above 84% of cities.

Paved land cover and Democratic lean

Places with extensive paved surfaces tend to lean Democratic; Boulder Hill, IL sits in the top tenth nationally on this measure. Paved ground does not change how people vote; it mostly reflects how urban and built-up a place is.

Why turnout in Boulder Hill looks the way it does

Turnout in Boulder Hill 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.

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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.