The East Bay is a subregion of the San Francisco Bay Area, California, United States and comprises Alameda and Contra Costa Counties. It lies on the eastern shores of the San Francisco Bay and San Pablo Bay and is generally considered to include not just the shorefront cities but the nearby inland valleys located on the east side of the Berkeley Hills.San Francisco Bay's eastern shore was once known as "Contra Costa" (literally "opposite coast"), a name now used for and exclusively associated with Contra Costa County, which occupies the East Bay shoreline's northern quarter and extensive inland areas, amounting to about half of the land area, with the remainder in Alameda County.
