Oakland is the most populous city and the county seat of Alameda County, California, United States. A major West Coast port, Oakland is the largest city in the East Bay region of the San Francisco Bay Area, the third-largest city overall in the Bay Area and the eighth-most populated city in California. With a population of 440,646 in 2020, it serves as the Bay Area's trade center and economic engine: the Port of Oakland is the busiest port in Northern California, and the fifth- or sixth-busiest in the United States of America. A charter city, Oakland was incorporated on May 4, 1852.