South Dakota leans Republican by roughly 28 points: about 36% of voters vote Democratic and 64% Republican.
About 69% of adults in South Dakota typically vote, above the U.S. average of about 62%. Among adults in South Dakota, ~25% vote Democratic, ~44% Republican, and ~31% don't vote. The map below shows estimated turnout by block group.
How South Dakota compares
Among states within 500 miles, South Dakota leans more Republican than 6 of 8 neighbors.
Politics vary noticeably by county within South Dakota. The southwest side runs the most Democratic (D+7) and the south side runs the most Republican (R+56), a spread of about 63 points.
Why South Dakota leans the way it does
This analysis examined 14,881 data points per state to find what predicts political lean and turnout. The items below are a few correlations that stood out for South Dakota, not a ranked or complete list of what matters most.
Rural areas vote Republican, and South Dakota sits in the bottom quarter on developed land relative to similar places.
Paved land cover and Republican lean
Places with little paved surface tend to lean Republican; South Dakota sits in the bottom quarter 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 South Dakota looks the way it does
Areas with strong routine healthcare access turn out at higher rates. South Dakota 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 67%, about 7 points above the U.S. average of 60%. Learn more about the findings and methodology on the political spectrum map.
Nearby States
States with Similar Populations
- Delaware D+17
- North Dakota R+30
- Alaska Even
- District of Columbia D+80
- Montana R+20
- Rhode Island D+17
- Vermont D+13
- Wyoming R+41
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.