Hillsdale is a Democratic stronghold. About 75% of voters here vote Democratic and 25% Republican.
About 57% of adults in Hillsdale typically vote, near the U.S. average of about 62%. Among adults in Hillsdale, ~43% vote Democratic, ~14% Republican, and ~43% don't vote. The map below shows estimated turnout by block group.
How Hillsdale compares
Among neighborhoods within 5 miles, Hillsdale leans more Democratic than 5 of 12 neighbors.
Hillsdale runs about 30 points more Democratic than California as a whole.
Politics vary noticeably by block within Hillsdale. The north side is the most Democratic-leaning (D+58) and the east side is the least Democratic-leaning (D+42), a spread of about 16 points.
Why Hillsdale leans the way it does
This analysis examined 14,881 data points per neighborhood to find what predicts political lean and turnout. The items below are a few correlations that stood out for Hillsdale, not a ranked or complete list of what matters most.
Dense areas vote Democratic. More than 99% of residents in Hillsdale live in densely developed areas, about 64 points above the U.S. average of 36%. High college attainment predicts Democratic voting, and Hillsdale sits in the top quarter (about 62%, above 83% of neighborhoods).
Developed land and Democratic lean
Places with a heavily developed built environment tend to lean Democratic; Hillsdale, San Mateo, CA sits in the top quarter nationally on this measure. Developed land does not change how people vote; it mostly reflects how urban a place is.
Why turnout in Hillsdale looks the way it does
Crowded housing lines up with lower turnout. About 8% of homes in Hillsdale have more than one occupant per room, above 87% of neighborhoods. Learn more about the findings and methodology on the political spectrum map.
Nearby Neighborhoods
- Marina Lagoon, San Mateo, CA D+50
- Beresford, San Mateo, CA D+52
- Sugerloaf, San Mateo, CA D+50
- Haywood Park, San Mateo, CA D+52
- East San Mateo, San Mateo, CA D+40
- Shoreview, San Mateo, CA D+44
- Downtown San Mateo, San Mateo, CA D+55
- Baywood-Aragon, San Mateo, CA D+51
- Western Hills, San Mateo, CA D+41
- North Central San Francisco, San Mateo, CA D+50
Neighborhoods with Similar Populations
- North Broadway, Newark, NJ D+32
- Granville Gardens, Chicago, IL D+40
- Carrick, Pittsburgh, PA D+18
- North Shores, North Bay Village, FL R+7
- Winter Gardens, Lakeside, CA R+20
- Pioneer Park, Las Vegas, NV D+16
- Glencliff, Nashville, TN D+21
- South Side, Mount Vernon, NY D+75
- Montopolis, Austin, TX D+54
- Maplewood, Fall River, MA R+6
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.