Yankton County leans heavily Republican by roughly 34 points: about 33% of voters vote Democratic and 67% Republican.
About 72% of adults in Yankton County typically vote, above the U.S. average of about 62%. Among adults in Yankton County, ~24% vote Democratic, ~48% Republican, and ~28% don't vote. The map below shows estimated turnout by block group.
How Yankton County compares
Among counties within 50 miles, Yankton County leans more Republican than 2 of 11 neighbors.
Yankton County runs about 6 points more Republican than South Dakota as a whole.
Politics vary noticeably by city within Yankton County. The northeast side is the most Republican-leaning (R+58) and the south side is the least Republican-leaning (R+21), a spread of about 37 points.
Why Yankton 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 Yankton County, not a ranked or complete list of what matters most.
Yankton County votes Republican even though it is densely developed (about 54%, far above the South Dakota average of 9%). State and regional patterns outweigh the Democratic lean that density usually predicts here.
Preventive-care access and voter turnout
Places with strong routine preventive-care access tend to turn out at a higher rate; Yankton County, SD sits in the top tenth nationally on this measure. Dental visits do not drive turnout; the rate reflects income, insurance, and healthcare access, which line up with who votes.
Why turnout in Yankton County looks the way it does
Areas with strong routine healthcare access turn out at higher rates. Yankton 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 69%, about 9 points above the U.S. average of 60%. Learn more about the findings and methodology on the political spectrum map.
Nearby Counties
- Cedar County, NE R+67
- Bon Homme County, SD R+58
- Clay County, SD D+2
- Knox County, NE R+56
- Turner County, SD R+53
- Hutchinson County, SD R+65
- Dixon County, NE R+56
- Union County, SD R+43
- Pierce County, NE R+72
- Lincoln County, SD R+29
Counties with Similar Populations
- McDonald County, MO R+65
- Teton County, WY D+16
- Saline County, MO R+36
- Pacific County, WA R+5
- Starke County, IN R+49
- Fayette County, IN R+54
- Meeker County, MN R+44
- Franklin County, GA R+66
- Antrim County, MI R+21
- Curry County, OR R+11
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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.