Island County leans slightly Democratic by roughly 10 points: about 55% of voters vote Democratic and 45% Republican.
About 80% of adults in Island County typically vote, above the U.S. average of about 62%. Among adults in Island County, ~44% vote Democratic, ~36% Republican, and ~20% don't vote. The map below shows estimated turnout by block group.
How Island County compares
Among counties within 50 miles, Island County leans more Democratic than 3 of 8 neighbors.
Island County runs about 8 points more Republican than Washington as a whole.
Politics vary noticeably by city within Island County. The south side runs the most Democratic (D+46) and the northeast side runs the most Republican (R+18), a spread of about 64 points.
Why Island 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 Island County, not a ranked or complete list of what matters most.
Areas with high college attainment vote Democratic. About 36% of adults in Island County hold a bachelor's degree, about 7 points above the U.S. average of 28%.
Preventive-care access and voter turnout
Places with strong routine preventive-care access tend to turn out at a higher rate; Island County, WA sits in the top 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 Island County looks the way it does
Areas with strong routine healthcare access turn out at higher rates. Island 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 68%, about 8 points above the U.S. average of 60%. High high-school completion lines up with higher turnout, and about 96% of adults in Island County have completed high school, above 96% of counties. Learn more about the findings and methodology on the political spectrum map.
Nearby Counties
- Jefferson County, WA D+45
- Skagit County, WA D+4
- Snohomish County, WA D+10
- San Juan County, WA D+50
- Clallam County, WA D+9
- Kitsap County, WA D+18
- Whatcom County, WA D+23
- King County, WA D+45
- Mason County, WA R+5
- Pierce County, WA D+12
Counties with Similar Populations
- Lincoln County, NC R+45
- Bannock County, ID R+25
- Muskingum County, OH R+41
- Angelina County, TX R+41
- Polk County, OR R+4
- Burke County, NC R+40
- Lawrence County, PA R+28
- Cullman County, AL R+76
- Dougherty County, GA D+48
- Elmore County, AL R+47
Sources and methodology
Precinct-level voting records used to fit the model come from Washington 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.