antioch,_california | ispartof | contra_costa_county,_california <tsp> antioch,_california | ispartof | california <tsp> california | language | vietnamese_language <tsp> contra_costa_county,_california | ispartof | san_francisco_bay_area <tsp> antioch,_california | leadertitle | united_states_house_of_representatives <sep> antioch is the third-largest city in contra costa county, california, united states the city is located in the east bay region of the san francisco bay area along the sacramento–san joaquin river delta the city's population was 115,291 at the 2020 census the city has grown substantially more diverse since the 1970s 
antioch. in contra costa county. california. is led by the u. s. house of representatives. contra costa county is part of the san francisco bay area of the state where one of the spoken languages is vietnamese.antioch is the third-largest city in contra costa county, california, united states