57331 is a Republican stronghold. About 14% of voters here vote Democratic and 86% Republican.
About 85% of adults in 57331 typically vote, above the U.S. average of about 62%. Among adults in 57331, ~12% vote Democratic, ~73% Republican, and ~15% don't vote. The map below shows estimated turnout by block group.
How 57331 compares
57331 sits in a sparsely populated area with few comparable zip codes nearby.
57331 runs about 42 points more Republican than South Dakota as a whole.
Why 57331 leans the way it does
This analysis examined 14,881 data points per zip code to find what predicts political lean and turnout. The items below are a few correlations that stood out for 57331, not a ranked or complete list of what matters most.
Rural areas vote Republican. About 5% of residents in 57331 live in densely developed areas, about 31 points below the U.S. average of 36%.
Population density and Republican lean
Places with low population density tend to lean Republican; 57331, SD sits in the bottom tenth nationally on this measure.
Why turnout in 57331 looks the way it does
Areas with strong routine healthcare access turn out at higher rates. 57331 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 68%, about 8 points above the U.S. average of 60%. High high-school completion lines up with higher turnout, and about 98% of adults in 57331 have completed high school, above 96% of zip codes. Learn more about the findings and methodology on the political spectrum map.
Nearby Zip Codes
Zip Codes with Similar Populations
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.