Custer County is a Republican stronghold. About 24% of voters here vote Democratic and 76% Republican.
About 63% of adults in Custer County typically vote, near the U.S. average of about 62%. Among adults in Custer County, ~15% vote Democratic, ~48% Republican, and ~37% don't vote. The map below shows estimated turnout by block group.
How Custer County compares
Custer County runs about 16 points more Republican than Idaho as a whole.
Politics vary noticeably by city within Custer County. The northwest side runs the most Democratic (D+3) and the southeast side runs the most Republican (R+64), a spread of about 66 points.
Why Custer 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 Custer County, not a ranked or complete list of what matters most.
Rural areas vote Republican. Fewer than 1% of residents in Custer County live in densely developed areas, about 17 points below the Idaho average of 18%.
Preventive-care access and voter turnout
Places with strong routine preventive-care access tend to turn out at a higher rate; Custer County, ID sits in the top quarter 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 Custer County looks the way it does
Areas with strong routine healthcare access turn out at higher rates. Custer 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%. Learn more about the findings and methodology on the political spectrum map.
Nearby Counties
- Blaine County, ID D+21
- Butte County, ID R+75
- Lemhi County, ID R+61
- Camas County, ID R+72
- Clark County, ID R+65
- Lincoln County, ID R+63
- Beaverhead County, MT R+42
- Boise County, ID R+50
- Valley County, ID R+41
- Gooding County, ID R+54
Counties with Similar Populations
- Kimble County, TX R+63
- Deuel County, SD R+54
- Menominee County, WI D+59
- Marshall County, SD R+31
- Barber County, KS R+69
- Holt County, MO R+61
- Phillips County, MT R+52
- Bath County, VA R+54
- Kittson County, MN R+34
- Mora County, NM D+18
All Local Stats
Home Services
Sources and methodology
Precinct-level voting records used to fit the model come from Idaho 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.