Pennington County leans Republican by roughly 28 points: about 36% of voters vote Democratic and 64% Republican.
About 67% of adults in Pennington County typically vote, near the U.S. average of about 62%. Among adults in Pennington County, ~24% vote Democratic, ~43% Republican, and ~33% don't vote. The map below shows estimated turnout by block group.
How Pennington County compares
Among counties within 50 miles, Pennington County is the least Republican-leaning.
Politically, Pennington County sits close to the rest of South Dakota.
Politics vary noticeably by city within Pennington County. The southeast side is the most Republican-leaning (R+67) and the west side is the least Republican-leaning (R+16), a spread of about 51 points.
Why Pennington 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 Pennington County, not a ranked or complete list of what matters most.
Pennington County votes Republican even though it is densely developed (about 59%, far above the South Dakota average of 9%). State and regional patterns outweigh the Democratic lean that density usually predicts here.
High-school completion and voter turnout
Places with high-school-completion-heavy adults tend to turn out at a higher rate; Pennington County, SD sits in the top quarter nationally on this measure.
Why turnout in Pennington County looks the way it does
Areas with strong routine healthcare access turn out at higher rates. Pennington 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%. High high-school completion lines up with higher turnout, and about 94% of adults in Pennington County have completed high school, above 87% of counties. Learn more about the findings and methodology on the political spectrum map.
Nearby Counties
- Meade County, SD R+51
- Custer County, SD R+53
- Lawrence County, SD R+37
- Fall River County, SD R+52
- Butte County, SD R+62
- Weston County, WY R+68
- Crook County, WY R+78
- Haakon County, SD R+71
- Jackson County, SD R+9
- Dawes County, NE R+39
Counties with Similar Populations
- Eaton County, MI R+8
- Madison County, MS R+5
- Bartow County, GA R+46
- Terrebonne Parish, LA R+42
- Warren County, NJ R+16
- LaSalle County, IL R+21
- Miami County, OH R+42
- Bradley County, TN R+48
- St. Lawrence County, NY R+18
- Hanover County, VA R+21
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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.