Sierra County leans Republican by roughly 18 points: about 41% of voters vote Democratic and 59% Republican.
About 62% of adults in Sierra County typically vote, near the U.S. average of about 62%. Among adults in Sierra County, ~25% vote Democratic, ~37% Republican, and ~38% don't vote. The map below shows estimated turnout by block group.
How Sierra County compares
Among counties within 50 miles, Sierra County leans more Republican than 3 of 5 neighbors.
Sierra County runs about 39 points more Republican than California as a whole. California leans Democratic overall, while Sierra County is one of the few Republican-leaning pockets.
Politics vary noticeably by city within Sierra County. The northeast side is the most Republican-leaning (R+24) and the southwest side is the least Republican-leaning (R+8), a spread of about 16 points.
Why Sierra 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 Sierra County, not a ranked or complete list of what matters most.
Sierra County votes against the grain of California. California leans Democratic overall, while Sierra County runs about 39 points more Republican.
Preventive-care access and voter turnout
Places with strong routine preventive-care access tend to turn out at a higher rate; Sierra County, CA 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 Sierra County looks the way it does
Areas with strong routine healthcare access turn out at higher rates. Sierra 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 65%, about 5 points above the U.S. average of 60%. High high-school completion lines up with higher turnout, and about 94% of adults in Sierra County have completed high school, above 84% of counties. Learn more about the findings and methodology on the political spectrum map.
Nearby Counties
- Plumas County, CA R+23
- Washoe County, NV D+3
- Nevada County, CA D+11
- Storey County, NV R+40
- Carson City, NV R+11
- Lassen County, CA R+37
- Douglas County, NV R+32
- Lyon County, NV R+42
- El Dorado County, CA R+13
- Yuba County, CA R+16
Counties with Similar Populations
- Tyrrell County, NC R+12
- Donley County, TX R+66
- Hudspeth County, TX R+45
- Harper County, OK R+80
- Coke County, TX R+72
- Emmons County, ND R+70
- Concho County, TX R+71
- Upton County, TX R+58
- Granite County, MT R+38
- Hand County, SD R+62
All Local Stats
Home Services
Sources and methodology
Precinct-level voting records used to fit the model come from California 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.