Lake County leans Democratic by roughly 22 points: about 61% of voters vote Democratic and 39% Republican.
About 71% of adults in Lake County typically vote, above the U.S. average of about 62%. Among adults in Lake County, ~43% vote Democratic, ~28% Republican, and ~29% don't vote. The map below shows estimated turnout by block group.
How Lake County compares
Among counties within 50 miles, Lake County leans more Democratic than 9 of 11 neighbors.
Lake County runs about 11 points more Democratic than Illinois as a whole.
Politics vary noticeably by city within Lake County. The east side is the most Democratic-leaning (D+40) and the northwest side is the least Democratic-leaning (Even), a spread of about 40 points.
Why Lake 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 Lake County, not a ranked or complete list of what matters most.
Dense areas vote Democratic. About 80% of residents in Lake County live in densely developed areas, about 43 points above the U.S. average of 36%. High college attainment predicts Democratic voting, and Lake County sits in the top quarter (about 47%, above 96% of counties).
Population density and Democratic lean
Places with high population density tend to lean Democratic; Lake County, IL sits in the top tenth nationally on this measure.
Why turnout in Lake County looks the way it does
Areas with strong routine healthcare access turn out at higher rates. Lake County 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 66%, about 6 points above the U.S. average of 60%. Learn more about the findings and methodology on the political spectrum map.
Nearby Counties
- Kenosha County, WI Even
- McHenry County, IL R+5
- Racine County, WI D+7
- DuPage County, IL D+14
- Kane County, IL D+13
- Cook County, IL D+42
- Walworth County, WI R+17
- Boone County, IL R+15
- DeKalb County, IL D+3
- Kendall County, IL Even
Counties with Similar Populations
- Denver County, CO D+53
- Davidson County, TN D+26
- Jackson County, MO D+24
- Hudson County, NJ D+27
- Polk County, FL R+18
- Norfolk County, MA D+30
- El Paso County, CO R+7
- Will County, IL D+6
- District of Columbia, DC D+80
- Bernalillo County, NM D+21
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.