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About Castro Valley

Castro Valley is a census-designated place (CDP) in Alameda County, California, United States. At the 2010 census, it was the fifth most populous unincorporated area in California and the twenty-third most populous in the United States. The population was 66,441 at the 2020 census.Castro Valley is named after Don Guillermo Castro, a noted 19th-century Californio ranchero who owned the land where the community is located. == History == Before the arrival of European settlers the area was settled by the Chocheño (also spelled Chochenyo or Chocenyo) subdivision of the Ohlone Native Americans. With the arrival of Europeans, they established Mission San Jose in 1797.