Madison County leans heavily Republican by roughly 36 points: about 32% of voters vote Democratic and 68% Republican.
About 55% of adults in Madison County typically vote, below the U.S. average of about 62%. Among adults in Madison County, ~18% vote Democratic, ~37% Republican, and ~45% don't vote. The map below shows estimated turnout by block group.
How Madison County compares
Among counties within 50 miles, Madison County leans more Republican than 1 of 6 neighbors.
Politically, Madison County sits close to the rest of Idaho.
Politics vary noticeably by city within Madison County. The southwest side is the most Republican-leaning (R+67) and the west side is the least Republican-leaning (R+39), a spread of about 28 points.
Why Madison 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 Madison County, not a ranked or complete list of what matters most.
Madison County votes Republican even though it is densely developed (about 67%, far above the Idaho average of 18%). State and regional patterns outweigh the Democratic lean that density usually predicts here.
Never-married share, developed land, and voter turnout
Places that combine a never-married-heavy adult population and a heavily developed built environment tend to turn out at a lower rate, as Madison County, ID does.
Why turnout in Madison County looks the way it does
Renters vote less often than owners. About 62% of households in Madison County rent, about 37 points above the U.S. average of 25%. High food insecurity lines up with lower turnout, and about 21% of adults in Madison County report food insecurity, above 80% of counties. Low high-school completion lines up with lower turnout, and about 98% of adults in Madison County have completed high school, in the top fraction of counties. Learn more about the findings and methodology on the political spectrum map.
Nearby Counties
- Jefferson County, ID R+71
- Fremont County, ID R+66
- Bonneville County, ID R+43
- Teton County, ID R+21
- Clark County, ID R+65
- Bingham County, ID R+54
- Teton County, WY D+16
- Bannock County, ID R+25
- Butte County, ID R+75
- Caribou County, ID R+73
Counties with Similar Populations
- Jackson County, IL D+7
- Jessamine County, KY R+35
- Navarro County, TX R+34
- Kerr County, TX R+45
- Columbia County, OR R+18
- Jackson County, AL R+71
- Gila County, AZ R+27
- Culpeper County, VA R+23
- McMinn County, TN R+61
- St. Charles Parish, LA R+25
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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.