Jefferson is a Republican stronghold. About 24% of voters here vote Democratic and 76% Republican.
About 68% of adults in Jefferson typically vote, above the U.S. average of about 62%. Among adults in Jefferson, ~16% vote Democratic, ~52% Republican, and ~32% don't vote. The map below shows estimated turnout by block group.
How Jefferson compares
Among cities within 25 miles, Jefferson leans more Republican than 19 of 39 neighbors.
Jefferson runs about 23 points more Republican than South Dakota as a whole.
Why Jefferson leans the way it does
Density, race composition, education, and family structure all sit close to their national averages in Jefferson. The lean here lands roughly where demographic data alone would predict.
Walkability and Democratic lean
Places with a highly walkable street grid tend to lean Democratic; Jefferson, SD sits in the top quarter nationally on this measure. A walkable street grid does not change how people vote; it mostly reflects how urban a place is.
Why turnout in Jefferson looks the way it does
Areas with strong routine healthcare access turn out at higher rates. Jefferson 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 70%, about 10 points above the U.S. average of 60%. Learn more about the findings and methodology on the political spectrum map.
Nearby Cities
- North Sioux City, SD R+38
- Willis, NE R+54
- Ponca, NE R+61
- Jackson, NE R+54
- Elk Point, SD R+42
- Sioux City, IA R+3
- South Sioux City, NE R+4
- Millnerville, IA R+54
- Westfield, IA R+54
- Junction City, SD R+52
Cities with Similar Populations
- Dolan Springs, AZ R+42
- Delbarton, WV R+77
- Lynnville, TN R+69
- Rock Port, MO R+60
- Hardaway, AL D+35
- Deerfield, MI R+44
- Conklin, MI R+48
- Gibraltar, MI R+20
- Fountain City, IN R+53
- Ramsey, IL R+66
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Sources and methodology
Precinct-level voting records used to fit the model come from South Dakota Secretary of State, 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.