Which California counties have the largest registered Democratic Party share as of 2024?
Executive summary
California’s registered Democrats made up roughly 46–47% of registered voters during the 2024 presidential primary reporting period, and the highest county-level Democratic concentrations were concentrated in the San Francisco Bay Area and in population-heavy Los Angeles County; the state’s official Report of Registration and related summaries are the source for county-by-county balances [1] [2] [3].
1. The statewide baseline: Democrats near a plurality in 2024
Statewide registration snapshots published ahead of the March 2024 presidential primary show the Democratic Party accounting for roughly 46.6% of registered voters in California, with Republicans about 24–24.4% and No Party Preference at roughly 21–22% — figures drawn from the Secretary of State’s 15-day and historical registration reports used for the 2024 primary [1] [4].
2. Where Democratic shares cluster: the Bay Area and Los Angeles dominate the map
The county-level Report of Registration issued by the Secretary of State for February 20, 2024, documents that the largest percentages and absolute numbers of registered Democrats are concentrated in Bay Area counties and in Los Angeles County: the county tables show Bay Area counties with strong Democratic percentages (for example, a Sonoma County listing in the SOS table records a Democratic percentage in the mid‑50s range in that report) and Alameda County’s registration snapshot lists 563,594 registered Democrats — underscoring both high shares and large raw totals in the Bay Area [2]. Independent reporting and analysis from the Public Policy Institute of California similarly emphasizes that most Democrats reside in Los Angeles County (about 28% of the state’s Democrats) or the San Francisco Bay Area (about 24%) — a population-concentration point that helps explain where the highest Democratic shares and totals appear on county rosters [3].
3. Numbers versus percentages: Los Angeles leads in raw Democratic voters, Bay Area in percentage strength
Public data make a distinction between where most Democrats live (by number) and which counties have the largest Democratic share of their own registrants (by percentage). The PPIC note that Los Angeles County contains the largest share of the state’s Democrats by population, while the SOS county tables show many Bay Area counties with some of the strongest Democratic majorities by percent [3] [2]. This means Los Angeles may top lists by raw Democratic voters, while smaller Bay Area counties often top lists by the share of local registrants who are Democrats [2] [3].
4. Exceptions and nuance: pockets of Democratic strength outside the Bay/LA axis
County-level dynamics are not uniform: several Central Valley and inland coastal counties contain districts or cities with sizable Democratic pluralities — examples appear in election reporting on specific congressional districts where registration can show a Democratic advantage in heavily Latino or urbanized pockets (CalMatters reporting on district registration percentages illustrates such local variation) — even as much of the state’s small rural counties remain Republican strongholds [5] [6].
5. Limitations of available public snapshots and how to read them
The Secretary of State’s February 2024 county PDF provides the authoritative county-by-county registration tables; the excerpts and summaries available in public reporting make clear the geography of Democratic strength but do not always present a single ranked list in every secondary summary, so precise “top ten” rankings should be read directly from the SOS county table for February 20, 2024 if an exact ordered list is required [2] [1]. Analysts and reporters (PPIC, CalMatters) frame the same source material in population-versus-share terms, which can produce different “largest” counties depending on whether the question asks for largest by number of registered Democrats or largest by Democratic percentage of county registration [3] [2].
Conclusion: answer in two parts — by share and by count
By percent-share, Bay Area counties (examples in the SOS county tables include counties such as Sonoma and others in the Bay Area that report Democratic majorities in the mid‑50s and above) sit at the top; by raw numbers, Los Angeles County contains the largest number of registered Democrats in California. The Secretary of State’s February 20, 2024 county registration report and the 15‑day pre‑primary summary are the authoritative sources for the detailed county figures and percentages [2] [1], and PPIC’s statewide profiles contextualize where Democrats live across the state [3].