Yamhill County leans slightly Republican by roughly 6 points: about 47% of voters vote Democratic and 53% Republican.
About 75% of adults in Yamhill County typically vote, above the U.S. average of about 62%. Among adults in Yamhill County, ~35% vote Democratic, ~40% Republican, and ~25% don't vote. The map below shows estimated turnout by block group.
How Yamhill County compares
Among counties within 50 miles, Yamhill County leans more Republican than 7 of 10 neighbors.
Yamhill County runs about 20 points more Republican than Oregon as a whole. Oregon leans Democratic overall, while Yamhill County is one of the few Republican-leaning pockets.
Politics vary noticeably by city within Yamhill County. The northeast side runs the most Democratic (D+5) and the southeast side runs the most Republican (R+32), a spread of about 36 points.
Why Yamhill 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 Yamhill County, not a ranked or complete list of what matters most.
Yamhill County votes Republican even though it is densely developed (about 53%, well above the Oregon average of 31%). State and regional patterns outweigh the Democratic lean that density usually predicts here. A high family-household share predicts Republican voting, and about 70% of households in Yamhill County are family households, above 79% of counties. Yamhill County runs against the grain of Oregon, a Republican-leaning pocket in a Democratic-leaning state.
Walkability and Democratic lean
Places with a highly walkable street grid tend to lean Democratic; Yamhill County, OR sits in the top tenth nationally on this measure. A walkable street grid does not change how people vote; it mostly reflects how urban a place is.
Why turnout in Yamhill County looks the way it does
Turnout in Yamhill 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
- Marion County, OR D+3
- Washington County, OR D+32
- Polk County, OR R+4
- Clackamas County, OR D+13
- Multnomah County, OR D+52
- Tillamook County, OR R+9
- Clark County, WA D+7
- Columbia County, OR R+18
- Benton County, OR D+42
- Linn County, OR R+25
Counties with Similar Populations
- Rockwall County, TX R+35
- Cass County, MO R+32
- Kankakee County, IL R+9
- Houston County, AL R+30
- Matanuska-Susitna Borough, AK R+33
- St. Lawrence County, NY R+18
- Carver County, MN R+8
- Bradley County, TN R+48
- Platte County, MO R+5
- Navajo County, AZ R+3
Sources and methodology
Precinct-level voting records used to fit the model come from Oregon Secretary of State, Elections Division, 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.