Sioux City is a true toss-up. About 49% of voters here vote Democratic and 51% Republican.
About 63% of adults in Sioux City typically vote, near the U.S. average of about 62%. Among adults in Sioux City, ~31% vote Democratic, ~32% Republican, and ~37% don't vote. The map below shows estimated turnout by block group.
How Sioux City compares
Among cities within 25 miles, Sioux City sits roughly in the middle of the political spectrum, with 2 neighbors leaning further in the place's direction and 37 leaning the other way.
Sioux City runs about 10 points more Democratic than Iowa as a whole.
Politics vary noticeably by neighborhood within Sioux City. The west side runs the most Democratic (D+11) and the northeast side runs the most Republican (R+27), a spread of about 38 points.
Why Sioux City leans the way it does
Density, race composition, education, and family structure all sit close to their national averages in Sioux City. The lean here lands roughly where demographic data alone would predict.
Population density and Democratic lean
Places with high population density tend to lean Democratic; Sioux City, IA sits in the top tenth nationally on this measure.
Why turnout in Sioux City looks the way it does
Turnout in Sioux City sits close to the national pattern. Routine healthcare access, homeownership, education, and food security all land near their national averages here. Learn more about the findings and methodology on the political spectrum map.
Nearby Cities
- South Sioux City, NE R+4
- North Sioux City, SD R+38
- Dakota City, NE R+40
- Sergeant Bluff, IA R+30
- Hinton, IA R+51
- Lawton, IA R+50
- Jefferson, SD R+52
- Jackson, NE R+54
- Neptune, IA R+53
- Bronson, IA R+51
Cities with Similar Populations
- Livermore, CA D+21
- Flagstaff, AZ D+31
- Youngstown, OH D+24
- Edinburg, TX Even
- Hawthorne, CA D+44
- Thornton, CO D+12
- Apex, NC D+15
- Bloomington, MN D+32
- Clifton, NJ Even
- Albany, GA D+44
Sources and methodology
Precinct-level voting records used to fit the model come from Iowa 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.