Castro Valley is a census-designated place in Alameda County, California, United States. As of the 2010 census, it is the fifth most populous unincorporated area in California and the twenty-third most populous in the United States. The population was 61,388 at the 2010 census.
Castro Valley is named after Don Guillermo Castro, who was a soldier in the Mexican army and a rancher.
First known for chicken ranches, Castro Valley eventually became a bedroom community.
Address 2740 Castro Valley Blvd, Castro Valley 94546, United States
Coordinates 37°41'40.386" N -122°5'8.676" E