Castro Valley, California
| Castro Valley, California | |
|---|---|
| Castro Valley, 2022 | |
| Location of Castro Valley within Alameda County, California | |
| Coordinates: 37°41′39″N 122°05′11″W / 37.69417°N 122.08639°W | |
| Country | United States | 
| State | California | 
| County | Alameda | 
| Named after | Don Guillermo Castro | 
| Government | |
| • State Senate | Tim Grayson (D) | 
| • State Assembly | Liz Ortega (D) | 
| • U. S. Congress | Eric Swalwell (D) | 
| Area | |
|  • Total | 17.07 sq mi (44.21 km2) | 
| • Land | 16.85 sq mi (43.64 km2) | 
| • Water | 0.22 sq mi (0.57 km2) 1.68% | 
| Elevation | 161 ft (49 m) | 
| Population  (2020) | |
|  • Total | 66,441 | 
| • Density | 3,943.55/sq mi (1,522.58/km2) | 
| Time zone | UTC-8 (PST) | 
| • Summer (DST) | UTC-7 (PDT) | 
| ZIP codes | 94546, 94552, 94541, | 
| Area code(s) | 510, 341 | 
| FIPS code | 06-11964 | 
| GNIS feature IDs | 1658237, 2407987 | 
Castro Valley is a census-designated place (CDP) in Alameda County, California, United States. At the 2020 census, it was the fourth most populous unincorporated area in California. The population was 66,441 at the 2020 census.
Castro Valley is named after Guillermo Castro, a noted 19th-century Californio ranchero who owned the land where the community is located.