Agencies:

• California Dept. of Finance (DOF)
  • Demographic, Economic, and Financial Research
• Census Bureau
  • American Factfinder
  • Enter a street address
• RAND California
  • California Statistics
    • Population and Demographic Statistics

Publications:

• California County Profiles
• California Quick Facts (People QuickFacts & Business QuickFacts)
• California Quick Links
• California Statistical Abstract
• Counting California
• Immigration and Migration
• Reports & Research Papers (Calif. Dept. of Finance, Demographic Research Unit)

Historical Census Data:

• Historical Census Browser 1790-1960 : Calif & county census data (Univ. of Virginia Library)
• Historical Census Populations of California State, Counties, Cities, Places, and Towns, 1850-2000 (Calif. Dept. of Finance)
• Historical Census Populations of Counties, Places, Towns, and Cities in California, 1850-1990 (Counting California)

See also : California Demographic Statistics