Arapahoe County leans Democratic by roughly 22 points: about 61% of voters vote Democratic and 39% Republican.
About 71% of adults in Arapahoe County typically vote, above the U.S. average of about 62%. Among adults in Arapahoe County, ~43% vote Democratic, ~28% Republican, and ~29% don't vote. The map below shows estimated turnout by block group.
How Arapahoe County compares
Among counties within 50 miles, Arapahoe County leans more Democratic than 8 of 11 neighbors.
Arapahoe County runs about 11 points more Democratic than Colorado as a whole.
Politics vary noticeably by city within Arapahoe County. The northwest side is the most Democratic-leaning (D+39) and the southeast side is the least Democratic-leaning (D+5), a spread of about 34 points.
Why Arapahoe 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 Arapahoe County, not a ranked or complete list of what matters most.
Dense areas vote Democratic. About 94% of residents in Arapahoe County live in densely developed areas, about 57 points above the U.S. average of 36%. High college attainment predicts Democratic voting, and Arapahoe County sits in the top quarter (about 46%, above 95% of counties). A high never-married share predicts Democratic voting, and about 33% of adults in Arapahoe County have never been married, above 78% of counties.
Paved land cover and Democratic lean
Places with extensive paved surfaces tend to lean Democratic; Arapahoe County, CO sits in the top tenth nationally on this measure. Paved ground does not change how people vote; it mostly reflects how urban and built-up a place is.
Why turnout in Arapahoe County looks the way it does
Turnout in Arapahoe County 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 Counties
- Denver County, CO D+53
- Douglas County, CO R+7
- Jefferson County, CO D+18
- Adams County, CO D+11
- Broomfield County, CO D+25
- Elbert County, CO R+46
- Boulder County, CO D+52
- Gilpin County, CO D+16
- Clear Creek County, CO D+21
- Weld County, CO R+17
Counties with Similar Populations
- Kent County, MI D+10
- Utah County, UT R+36
- Providence County, RI D+20
- Bucks County, PA Even
- Monmouth County, NJ R+8
- Tulsa County, OK Even
- Ocean County, NJ R+39
- Jefferson County, AL D+20
- Bernalillo County, NM D+21
- District of Columbia, DC D+80
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Sources and methodology
Precinct-level voting records used to fit the model come from Colorado 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.