Alameda County

County in north-central California, USA; area 1,906 sq km/736 sq mi; population (1990) 1,279,200. Its administrative headquarters is Oakland. The county extends from the east shore of San Francisco Bay, over the San Leandro and other hills, east to the edge of the San Joaquin River Valley. Oakland, Alameda, Berkeley, San Leandro, Hayward, Fremont, and other seaport, industrial, and suburban cities lie on or near the bay. To the east are the wine producing Livermore Valley and other agricultural and quarrying areas.