Day County leans heavily Republican by roughly 42 points: about 29% of voters vote Democratic and 71% Republican.
About 65% of adults in Day County typically vote, near the U.S. average of about 62%. Among adults in Day County, ~19% vote Democratic, ~46% Republican, and ~35% don't vote. The map below shows estimated turnout by block group.
How Day County compares
Among counties within 50 miles, Day County leans more Republican than 3 of 6 neighbors.
Day County runs about 12 points more Republican than South Dakota as a whole.
Politics vary noticeably by city within Day County. The south side is the most Republican-leaning (R+45) and the east side is the least Republican-leaning (R+32), a spread of about 14 points.
Why Day 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 Day County, not a ranked or complete list of what matters most.
Rural areas vote Republican. About 7% of residents in Day County live in densely developed areas, about 29 points below the U.S. average of 36%.
Population density and Republican lean
Places with low population density tend to lean Republican; Day County, SD sits in the bottom tenth nationally on this measure.
Why turnout in Day County looks the way it does
Areas with strong routine healthcare access turn out at higher rates. Day 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 67%, about 7 points above the U.S. average of 60%. Learn more about the findings and methodology on the political spectrum map.
Nearby Counties
- Marshall County, SD R+31
- Roberts County, SD R+19
- Codington County, SD R+42
- Clark County, SD R+57
- Grant County, SD R+52
- Brown County, SD R+35
- Big Stone County, MN R+33
- Hamlin County, SD R+64
- Traverse County, MN R+42
- Spink County, SD R+50
Counties with Similar Populations
- Cherry County, NE R+67
- Norton County, KS R+71
- Haskell County, TX R+65
- Harper County, KS R+65
- Mahnomen County, MN R+16
- Greer County, OK R+67
- Floyd County, TX R+50
- Stark County, IL R+47
- Morris County, KS R+52
- Hartley County, TX R+76
All Local Stats
Home Services
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.