| A picture of the giant locomotive on the other side. The Big Boy was the largest steam locomotive to ever be built. They were built by ALCO between 1940 and 1944. Union Pacific was the only railroad to purchase any of these 4-6-6-4 monsters and were mainly used to haul heavy freight up and down the Rocky Mountains. Cheyenne was where most of the Big Boys would begin and end their journeys to and from the mountain ranges. Twenty-Five of these huge locomotives were purchased by the UP and all of them were retired in favor of newer, more efficient diesel power in the mid 1950s. |