Alameda County, California

Alameda County ( ) is located in the U.S. state of California. 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.

The Spanish word alameda means either "a grove of poplar trees or a tree lined street". The name was originally used to describe the Arroyo de la Alameda; the willow and sycamore trees along the banks of the river reminded the early Spanish explorers of a road lined with trees.

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.