Oakland is the seat of Alameda County, just east of San Francisco. It lies between Berkeley and Hayward along Interstate 680, near the San Francisco Bay and the Pacific Ocean. Following the Mexican War of 1846-48, when the victorious United States took over California, the Oakland settlement became an entry port and supply depot for prospectors headed to recently discovered gold fields. The city's new status as the transcontinental railroad's western terminus put it on the map after 1869. Today, Oakland is a major industrial hub and West Coast port. The city is among the country's most ethnically diverse communities. The African American Museum and Library preserves the history of blacks living in California and elsewhere in the West. Oakland's Lakeside Park surrounds Lake Merritt, the country s largest urban saltwater body