Big Boy

Big Boy is the popular name of the American Locomotive Company 4000-class 4-8-8-4 articulated, coal-fired, steamlocomotives manufactured between 1941 and 1944 and operated by the Union Pacific Railroad until 1959. The Big Boy fleet totaled twenty five locomotives that were used primarily in the Wyoming Division to haul freight over the Wasatch range between Green River, Wyoming and Ogden, Utah.