The Union Pacific 4000 series "Big Boy" steam locomotives are arguably the largest steam engines ever built. Weighing over 1.2 million pounds the Big Boy locomotives where commonly found along the Union Pacific's mainline between Cheyenne and Laramie Wyoming over the famous Sherman Hill. Capable of moving nearly 5 miles of freight unassisted on flat track, the Big Boy's where the largest steam engines to see service on the UP and where vital to the war effort, moving billions of tons of war supplies between the 25 engines to see service. Recently the Union Pacific has undertaken the restoration of UP 4014, one of 8 surviving Big Boys, and is working to return it to operation by 2019. UP 4014 will join the Union Pacific's steam program with 3985 and 844 and pull excursions all over the US.