Antioch (formerly, East Antioch, Smith's Landing, and Marshs Landing) is a city in Contra Costa County, California, United States. Located in the East Bay region of the San Francisco Bay Area along the San Joaquin-Sacramento River Delta, it is a suburb of San Francisco and Oakland. The city's population was 102,372 at the 2010 census and estimated to be 108,930 in 2014.