1) This was the San Francisco Bay ferry steamer 'Eureka' of the Northwestern Pacific Railroad Co.2) It was only a ferry, limited to the SF-Sausalito runs. 3) The date can only be c.1924-1941. 'Eureka' was built and launched in 1924 and sold to Southern Pacific Co., and repainted with SP markings in mid-1941 and placed on the SF-Oakland ferry run.A fine point: The 'Eureka' has been preserved intact and is part of the historic floating collections of the National Maritime Museum, SF.
Van Covert Martin (Tue,) studied this question.