Seneca is a Republican stronghold. About 16% of voters here vote Democratic and 84% Republican.
About 67% of adults in Seneca typically vote, near the U.S. average of about 62%. Among adults in Seneca, ~11% vote Democratic, ~57% Republican, and ~32% don't vote. The map below shows estimated turnout by block group.
How Seneca compares
Among cities within 25 miles, Seneca leans more Republican than 6 of 14 neighbors.
Seneca runs about 38 points more Republican than South Dakota as a whole.
Why Seneca 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 Seneca, not a ranked or complete list of what matters most.
Rural areas with a high white share vote Republican. Seneca sits in the bottom quarter on density and about 97% of residents are non-Hispanic white, about 16 points above the South Dakota average of 81%.
Population density and Republican lean
Places with low population density tend to lean Republican; Seneca, SD sits in the bottom tenth nationally on this measure.
Why turnout in Seneca looks the way it does
Areas with high high-school completion turn out at higher rates. About 97% of adults in Seneca have completed high school, about 7 points above the U.S. average of 90%. Learn more about the findings and methodology on the political spectrum map.
Nearby Cities
- Spring Lake, SD R+63
- Logan, SD R+70
- Onaka, SD R+67
- Norbeck, SD R+69
- Tolstoy, SD R+69
- Faulkton, SD R+65
- Orient, SD R+66
Cities with Similar Populations
- Meadville, WV R+68
- East Pharsalia, NY R+46
- Hawkinsville, TX R+63
- Wingston, OH R+49
- Purdy, WI R+10
- Higgins Corners, PA R+58
- Tasco, KS R+86
- Cairo, TN R+63
- Napier, IA R+8
- Willimantic, ME R+39
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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.