Antioch (formerly, East Antioch, Smith's Landing, and Marshs Landing) is a city in Contra Costa County, California. 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 90,532 at the U.S. 2000 census, and was estimated to have grown to 100,219 in 2008.