The Bay Area and Los Angeles have grown far more Democratic than the rest of the state

Source: California Secretary of State.
NOTES: Trend lines show the Democratic share of votes cast in each presidential election (excludes third-party candidates). “Bay Area/north coast” includes Alameda, Contra Costa, Humboldt, Lake, Marin, Mendocino, Napa, San Francisco, San Mateo, Santa Clara, Santa Cruz, Solano, and Sonoma Counties. “Central/south coast (not LA)” includes Monterey, Orange, San Benito, San Diego, San Luis Obispo, Santa Barbara, and Ventura Counties. “Los Angeles” includes only Los Angeles County, and “Interior” includes all other counties.