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 107,100 in 2013. Antioch is one of the oldest towns in California, having been founded in 1850. The year following the discovery of gold, there was a plague that overtook the city and wiped out most of the population.