Built by Baldwin Locomotive Works, the Southern Pacific P-10 Pacifics were 4-6-2 Pacific steam locomotives. Pacifics were designed for passenger service where high speeds was important. The Pacifics started life with the Southern Pacific on long distance passenger trains. But as bigger and better locomotives entered service, they were transferred to shorter passenger service routes and commuter service. By the late 1950's just about all steam locomotives, including the P-10 Pacifics had been retired from service with Southern Pacific.