continued dual-numbered with 89 through Quincy. Highway 24 split from 89 near Graeagle, and continued east through Portola east until its terminus at U.S. Route 395. Parts of the same route were also sometimes designated as State Route 84. At least one published map from the 1960s incorrectly showed Route 24 extending eastward from Interstate 680 in Walnut Creek to Route 4 in Pittsburg that followed the Ygnacio Valley Road-Kirker Pass Road-Railroad Avenue corridor, presumably as a future extension that never materialized. A 1970 State Highway Map shows this corridor as a future Route 24 bypass. A 1956 version of Thomas Brothers maps shows Mt. Diablo Blvd. where present day Northgate Road is and labeled as Route 24, winding and climbing the mountain. Exit list Mileage is measured from SR 24's original western terminus, now part of Interstate 980. See also References External links California @ AARoads - State Route 24 Caltrans: Route 24 highway conditions California Highways: SR 24 Alternate routes considered for Route 24 in Oakland 024 024 024 State Route 024 State Route 024 Transportation in Oakland, California Lafayette, California Orinda, California Walnut Creek, California