High Quality Content by WIKIPEDIA articles! Concord is the largest city in Contra Costa County, California, USA, and the 202nd largest in the U.S. As of the 2000 census, the city had a total population of 121,780. Originally founded in 1869 as the community of Todos Santos by Salvio Pacheco, the name was changed to Concord within months. The city is a major regional suburban East Bay center within the San Jose/San Francisco Metropolitan Area, and is located just 31 miles east of San Francisco.