Waterloo leans Republican by roughly 18 points: about 41% of voters vote Democratic and 59% Republican.
About 90% of adults in Waterloo typically vote, above the U.S. average of about 62%. Among adults in Waterloo, ~37% vote Democratic, ~53% Republican, and ~10% don't vote. The map below shows estimated turnout by block group.
How Waterloo compares
Among cities within 25 miles, Waterloo leans more Republican than 34 of 77 neighbors.
Waterloo runs about 17 points more Republican than Wisconsin as a whole.
Politics vary noticeably by neighborhood within Waterloo. The northeast side is the most Republican-leaning (R+35) and the southwest side is the least Republican-leaning (R+12), a spread of about 24 points.
Why Waterloo 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 Waterloo, not a ranked or complete list of what matters most.
Waterloo votes Republican even though it is densely developed (about 29%, about 8 points below the U.S. average of 36%). State and regional patterns outweigh the Democratic lean that density usually predicts here.
Population density and Democratic lean
Places with high population density tend to lean Democratic; Waterloo, WI sits in the top quarter nationally on this measure.
Why turnout in Waterloo looks the way it does
Turnout in Waterloo 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 Cities
- Portland, WI R+39
- Marshall, WI R+3
- York Center, WI R+6
- Milford, WI R+16
- Lake Mills, WI R+12
- Nora, WI D+6
- Danville, WI R+37
- Grellton, WI R+37
- London, WI Even
- Reeseville, WI R+44
Cities with Similar Populations
- Florence, TX R+47
- Montebello, NY R+13
- Lake Odessa, MI R+37
- Elko New Market, MN R+28
- Oak Hill, OH R+63
- Ashford, AL R+65
- Bucksport, ME R+17
- Foster, RI R+15
- Crooksville, OH R+54
- Dryden, MI R+43
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Sources and methodology
Precinct-level voting records used to fit the model come from Wisconsin Elections Commission, 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.