The GS-6 is a class of semi-streamlined 4-8-4 "Northern" type steam locomotive operated by the Southern Pacific Railroad (SP) from 1943 to 1958 and the Western Pacific Railroad (WP) from 1943 to 1953. A total of sixteen were built by the Lima Locomotive Works, numbered 4460 through 4469 by SP and 481 through 486 by WP. GS stands for "Golden State" or "General Service."