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Alameda County, California

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Please add profiles of those who were born, lived or died in Alameda County, California.


The county was formed on March 25, 1853, from a large portion of Contra Costa County and a smaller portion of Santa Clara County.

The county seat at the time of the county's formation was located at Alvarado, now part of Union City. In 1856, it was moved to San Leandro, where the county courthouse was destroyed by the devastating 1868 quake on the Hayward Fault. The county seat was then re-established in the town of Brooklyn from 1872-1875. Brooklyn is now part of Oakland, which has been the county seat since 1873.

Much of what is now considered an intensively urban region, with major cities, was developed as a trolley car suburb of San Francisco in the late 19th and early 20th centuries. The historical progression from Native American tribal lands to Spanish, then Mexican ranches, then to farms, ranches, and orchards, then to multiple city centers and suburbs, is shared with the adjacent and closely associated Contra Costa County.

Adjacent Counties


+Denotes County Seat

  • Alameda
  • Albany
  • Berkeley
  • Dublin
  • Emeryville
  • Fremont
  • Hayward
  • Livermore
  • Newark
  • Oakland
  • Piedmont
  • Pleasanton
  • San Leandro
  • Union City



10th Street Market

The Joaquin Miller House

The Camron-Stanford House

Casa Peralta

The Dunsmuir House

Eden Congregational Church

The Federal Realty Building

Founders' Rock

Green Shutter Hotel

The Greek Theatre

Heinold's First and Last Chance Saloon

Livermore Carnegie Library

Meek Mansion

Oakland City Hall

Oakland Hotel

The Pardee Home

Ardenwood Historic Farm

The Peralta Home

Basilica of St. Joseph

Old St. Raymond's Church

The Thorsen House

USS Hornet CV-12