Castro Valley, California

Castro Valley is a census-designated place (CDP) in Alameda County, California, United States. As of the 2020 census, it is the fourth most populous unincorporated area in California. The population was 66,441 at the 2020 census.^[4]

Castro Valley, California
CDP
Castro Valley, c. 1970
Location of Castro Valley within Alameda County, California
Castro Valley, California Location in the United States
Coordinates: 37°41′39″N 122°05′11″W[1]
Country	United States
State	California
County	Alameda
Area [2]
• 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 [3]	161 ft (49 m)
Population  (2020)[4]
• 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, 94578, 94541, 94542
Area code(s)	510, 341
FIPS code	06-11964
GNIS feature IDs	1658237, 2407987