Highway 24 was designated in 1932 in conjunction with the ongoing construction of the Broadway Low Level Tunnel (subsequently renamed the Caldecott Tunnel) which opened in 1937, connecting with the new Eastshore Highway and the approaches to the new Bay Bridge by way of Tunnel Road and Ashby Avenue through Berkeley west of the Berkeley Hills, and routed along Mount Diablo Boulevard through Contra Costa County east of the hills. Before either the bridge or the tunnel were completed, Highway 24 was provisionally routed starting from downtown Oakland at the major intersection of San Pablo and Broadway, which was also the terminal point of US 40 and State Highway 17. From this point, Highway 24 proceeded northward along Broadway to College Avenue, then along College to Claremont Avenue, up Claremont to Tunnel Road, then up into the Berkeley Hills on Tunnel Road to the old Intercounty Tunnel (also called the Kennedy Tunnel), through the tunnel into Contra Costa County.