Lamorinda is an area within Contra Costa County, California in the United States. The name is a portmanteau from the names of the three cities that make up the region: Lafayette, Moraga and Orinda. Lamorinda sits east of the Berkeley Hills between the Caldecott Tunnel and Walnut Creek. It is also referred to as the "Highway 24" corridor, referring to the state highway that is the primary thoroughfare in the region. Many residents commute west through the tunnel to San Francisco and Oakland or east to Walnut Creek and Concord.