Alameda County is located in the state of California in the United States. As of the 2020 census, the population was 1,682,353, making it the 7th-most populous county in the state and 21st most populous nationally. The county seat is Oakland. Alameda County is in the San Francisco Bay Area, occupying much of the East Bay region. Alameda County is part of the San Francisco–Oakland–Berkeley, CA Metropolitan Statistical Area, and the San Jose–San Francisco–Oakland, CA Combined Statistical Area.