CA-10 — Registration, Primary & Demographics

Prop 50 lines · 501,553 registered · dot size = city population

District Data

Incumbent Mark DeSaulnier (D) · reg. D+26

Total registered voters

501,553The actual district — not whole-county totals

No Party Preference (113,804) outnumbers Republicans (111,657). The purple swing bloc is the whole ballgame — it's why purple is the loudest color on this map.

Map view

Politics
City registration breakdown
Demographic overlays

Dot size = city population (bigger dot = more people). The registration overlays use real city data; unincorporated communities show as hollow grey — California publishes party registration for incorporated cities only.

Two-county split

454,207Contra Costa · 90.6%
47,346Alameda · 9.4%

Toggle the Alameda crossover layer to see exactly where the ~1-in-10 Alameda slice sits.

June 2, 2026 primary · districtwide

DeSaulnier (D)132,24659.7%
Frese (R) ✅28,67112.9%
Piccinini (R)25,48711.5%
Griffiths (R)14,7676.7%
3 other Democrats20,4109.2%
~44.2%Primary turnout
31.1%All-GOP vote (3 R's)

Certified — CA Secretary of State Statement of Vote, June 2, 2026 primary. County-level.

Demographics (overlay data)

760,066residents · 2020 Census

Income/age/education aren't tabulated on the new lines — city overlays use Census ACS; district income ~$128k / age 40.5 / 44% college (Contra Costa proxy). The voting-eligible population is whiter (57.6%) than residents.

Layers

Sources & caveats

Boundary: CA GIS (Prop 50, GEOID 0610). District & city registration: CA SoS Report of Registration, May 18 2026 (incorporated cities only — unincorporated not published). Primary: CA SoS certified Statement of Vote, June 2026. Demographics: CA SDMG + Census ACS 5-yr. City lean is qualitative; income top-coded at $250k; Port Costa/Byron figures directional; San Leandro is mostly in CA-12 (shown for reference).
Paid for by Frese For Congress.

Paid for by Frese For Congress.