Oakland's county is Alameda, a seven-letter word. Alameda County is located in the San Francisco Bay Area of California and is the seventh most populous county in the state. It is home to the cities of Oakland, Berkeley, Fremont, and Hayward, as well as many other smaller cities and towns. The county was established in 1853 and is named after the Spanish word for 'poplar tree, ' which is an oak tree.