Jefferson County leans Republican by roughly 20 points: about 40% of voters vote Democratic and 60% Republican.
About 84% of adults in Jefferson County typically vote, above the U.S. average of about 62%. Among adults in Jefferson County, ~34% vote Democratic, ~50% Republican, and ~16% don't vote. The map below shows estimated turnout by block group.
How Jefferson County compares
Among counties within 50 miles, Jefferson County leans more Republican than 9 of 11 neighbors.
Jefferson County runs about 20 points more Republican than Wisconsin as a whole.
Politics vary noticeably by city within Jefferson County. The east side is the most Republican-leaning (R+41) and the west side is the least Republican-leaning (R+10), a spread of about 30 points.
Why Jefferson County leans the way it does
Density, race composition, education, and family structure all sit close to their national averages in Jefferson County. The lean here lands roughly where demographic data alone would predict.
Cancer-screening access and voter turnout
Places with high colon-cancer-screening access tend to turn out at a higher rate; Jefferson County, WI sits in the top quarter nationally on this measure. Cancer screening does not drive turnout; it reflects income, insurance, and healthcare access.
Why turnout in Jefferson County looks the way it does
Areas with strong routine healthcare access turn out at higher rates. Jefferson 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 68%, about 8 points above the U.S. average of 60%. Learn more about the findings and methodology on the political spectrum map.
Nearby Counties
- Dodge County, WI R+30
- Waukesha County, WI R+14
- Walworth County, WI R+17
- Rock County, WI Even
- Dane County, WI D+48
- Washington County, WI R+28
- Columbia County, WI R+17
- Milwaukee County, WI D+41
- Ozaukee County, WI R+7
- Green County, WI R+11
Counties with Similar Populations
- Orange County, TX R+59
- Buchanan County, MO R+23
- Glynn County, GA R+14
- Cascade County, MT R+25
- Wood County, WV R+41
- Orangeburg County, SC D+28
- Newport County, RI D+23
- Chemung County, NY R+14
- Dougherty County, GA D+48
- Crawford County, PA R+39
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.