Sioux County is a Democratic stronghold. About 77% of voters here vote Democratic and 23% Republican.
About 52% of adults in Sioux County typically vote, below the U.S. average of about 62%. Among adults in Sioux County, ~40% vote Democratic, ~12% Republican, and ~48% don't vote. The map below shows estimated turnout by block group.
How Sioux County compares
Among counties within 50 miles, Sioux County is the most Democratic-leaning.
Sioux County runs about 90 points more Democratic than North Dakota as a whole. North Dakota leans Republican overall, while Sioux County is one of the few Democratic-leaning pockets.
Politics vary noticeably by city within Sioux County. The east side runs the most Democratic (D+72) and the west side runs the most Republican (R+4), a spread of about 76 points.
Why Sioux 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 Sioux County, not a ranked or complete list of what matters most.
Sioux County votes against the grain of North Dakota. North Dakota leans Republican overall, while Sioux County runs about 90 points more Democratic. A high never-married share predicts Democratic voting, and about 55% of adults in Sioux County have never been married, in the top fraction of counties.
Preventive-care access and voter turnout
Places with limited routine preventive-care access tend to turn out at a lower rate; Sioux County, ND sits in the bottom tenth 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 Sioux County looks the way it does
Areas with limited routine healthcare access turn out at lower rates. Sioux County is in the bottom quarter nationally for routine-care measures such as insurance coverage, preventive screenings, and dental visits. The dental-visit rate here is about 40%, about 24 points below the North Dakota average of 64%. Renters vote less often than owners, and about 54% of households in Sioux County rent, compared to around 24% in nearby counties. High food insecurity lines up with lower turnout, and about 44% of adults in Sioux County report food insecurity, in the top fraction of counties. Learn more about the findings and methodology on the political spectrum map.
Nearby Counties
- Emmons County, ND R+70
- Corson County, SD D+38
- Campbell County, SD R+66
- Burleigh County, ND R+32
- Morton County, ND R+49
- Walworth County, SD R+56
- Grant County, ND R+71
- McIntosh County, ND R+61
- Logan County, ND R+75
- Kidder County, ND R+61
Counties with Similar Populations
- Corson County, SD D+38
- Chase County, NE R+71
- Sargent County, ND R+50
- Red Lake County, MN R+47
- Columbia County, WA R+51
- Mason County, TX R+56
- Clark County, SD R+57
- Wells County, ND R+58
- Kearny County, KS R+71
- Edmunds County, SD R+60
Sources and methodology
Precinct-level voting records used to fit the model come from North 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.