#trainmuseum

The Big Boy is a 4000 class 4-8-8-4 Mallet articulated steam locomotive manufactured by the American Locomotive Company (ALCO) between 1941 and 1944 and operated by the Union Pacific Railroad.The last revenue freight pulled by a Big Boy was in July of 1959. Most were retired in 1961.In 2013, UP re-acquired the No. 4014 locomotive and rebuilt it to operating condition. In May 2019, it concluded its restoration and returned to service.