Why Does Only One Big Boy Survive Today?

Twenty-five Union Pacific Big Boys were built — and only one runs today. Big Boy No. 4014 is the sole operational example of what was once the largest steam locomotive class in American history, returned to service in 2019 after a seven-year restoration by Union Pacific's mechanical department in Cheyenne, Wyoming. The other twenty-four are either scrapped or standing as static museum displays — preserved in place but never again to move under their own power. The combination of scrap economics in the 1950s and 1960s, the speed of diesel retirement, and the narrow window available for preservation efforts produced a survival rate of eight from twenty-five, and an operational survival rate of one from eight.