After the GS-1 and GS-2, Southern Pacific decided to design additional express locomotives in the “Golden State” series for higher speeds. By increasing the size of the drivers from 73.5 to 80 inches, the GS-3 was created, which also pulled the “Coast Daylight”. Since there were many gradients on the line between Los Angeles and San Francisco, the tractive force was compensated for by a longer cylinder stroke and higher boiler pressure.
Like the GS-2, the GS-3 stood out with its partial streamlined fairing and striking color scheme of orange, red, silver and black. After 14 GS-3s built in 1937, a total of 28 GS-4s were built in 1941 and 1942. These differed from the GS-3 mainly in a booster in the trailing bogie. They also had a faster-acting, electro-pneumatic brake, which was later removed.
During World War II, the Southern Pacific wanted to build more locomotives of this type, but the government only allowed the construction of freight locomotives. Thus, the abbreviation GS was reinterpreted from “Golden State” to “General Service”, which would indicate that these locomotives were suitable for freight and passenger trains.
In 1942 only two GS-5s were built, which now had roller bearings on all axles. The later developed GS-6 again had smaller wheels and was actually suitable for mixed service. The GS-3 to GS-5 were retired in 1957 and 1958 and largely scrapped. Among the only two members of the GS series that still exist today is the GS-4 No. 4449, which is operational.