Oldham leans heavily Republican by roughly 48 points: about 26% of voters vote Democratic and 74% Republican.
About 63% of adults in Oldham typically vote, near the U.S. average of about 62%. Among adults in Oldham, ~16% vote Democratic, ~47% Republican, and ~37% don't vote. The map below shows estimated turnout by block group.
How Oldham compares
Among cities within 25 miles, Oldham leans more Republican than 3 of 23 neighbors.
Oldham runs about 18 points more Republican than South Dakota as a whole.
Why Oldham 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 Oldham, not a ranked or complete list of what matters most.
Rural areas vote Republican. About 4% of residents in Oldham live in densely developed areas, about 5 points below the South Dakota average of 9%.
Preventive-care access and voter turnout
Places with strong routine preventive-care access tend to turn out at a higher rate; Oldham, SD sits in the top quarter 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 Oldham looks the way it does
Areas with strong routine healthcare access turn out at higher rates. Oldham 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%. High high-school completion lines up with higher turnout, and about 96% of adults in Oldham have completed high school, above 83% of cities. Learn more about the findings and methodology on the political spectrum map.
Nearby Cities
- Ramona, SD R+50
- Lake Preston, SD R+49
- Cloverleaf Colony, SD R+53
- Sinai, SD R+52
- Arlington, SD R+49
- Hetland, SD R+50
- Junius, SD R+50
- DeSmet, SD R+52
- Winfred, SD R+52
- Prairie Village, SD R+49
Cities with Similar Populations
- Hatcher, KY R+59
- Silver Creek, WI R+44
- East Deering, NH R+12
- Reagan, TX R+70
- Graham, MS R+87
- New Grand Chain, IL R+62
- Kirschnerville, NY R+37
- Grandin, ND R+42
- Osterdock, IA R+50
- Valeda, KS R+63
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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.