Janesville leans slightly Democratic by roughly 6 points: about 53% of voters vote Democratic and 47% Republican.
About 79% of adults in Janesville typically vote, above the U.S. average of about 62%. Among adults in Janesville, ~42% vote Democratic, ~37% Republican, and ~21% don't vote. The map below shows estimated turnout by block group.
How Janesville compares
Among cities within 25 miles, Janesville leans more Democratic than 67 of 72 neighbors.
Janesville runs about 6 points more Democratic than Wisconsin as a whole.
Politics vary noticeably by neighborhood within Janesville. The east side runs the most Democratic (D+8) and the northwest side runs the most Republican (R+9), a spread of about 17 points.
Why Janesville 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 Janesville, not a ranked or complete list of what matters most.
Dense areas vote Democratic. About 77% of residents in Janesville live in densely developed areas, about 40 points above the U.S. average of 36%. A high never-married share predicts Democratic voting, and about 31% of adults in Janesville have never been married, above 79% of cities.
Paved land cover and Democratic lean
Places with extensive paved surfaces tend to lean Democratic; Janesville, WI 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 Janesville looks the way it does
Turnout in Janesville 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
- Afton, WI R+11
- Milton, WI R+19
- Milton Junction, WI R+23
- Garden Village, WI R+12
- Hanover, WI R+23
- Avalon, WI R+32
- Indianford, WI R+21
- Newville, WI R+18
- Tiffany, WI R+17
- Johnstown, WI R+28
Cities with Similar Populations
- Statesville, NC R+20
- Union City, NJ D+14
- Morgantown, WV D+13
- Huntington Park, CA D+37
- Leesburg, VA D+17
- Passaic, NJ D+5
- Palatine, IL D+19
- San Rafael, CA D+46
- Centreville, VA D+26
- Cheektowaga, NY D+11
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.