Concord ( KON-kerd) is the most populous city in Contra Costa County, California, United States. According to an estimate completed by the United States Census Bureau, the city had a population of 129,295 in 2019, making it the eighth largest city in the San Francisco Bay Area. Founded in 1869 as Todos Santos by don Salvio Pacheco II, a noted Californio ranchero, the name was later changed to Concord. The city is a major regional suburban East Bay center within the San Francisco Bay Area, and is 29 miles (47 kilometers) east of San Francisco. The United States Census Bureau defines an urban area in the East Bay which is separated from the San Francisco–Oakland urban area and with Concord as the principal city: the Concord–Walnut Creek, CA urban area had a population of 538,583 as of the 2020 census, making it the 80th largest in the United States.