In the midst of World War II, the company was tasked with creating a more powerful steam engine that was capable of hauling heavy loads on a single locomotive, thus birthing the Big Boy.

Twenty-five Big Boy locomotives were built for Union Pacific ... The world's largest steam engine is coming back to Colorado. Union Pacific will bring Big Boy No. 4014 through Colorado from ...

There are steam locomotives, and then there’s “Big Boy.” At 604 tons and 132 feet long and with a 4-8-8-4-wheel arrangement, it is the largest, most powerful steam locomotive in the world.

In early September, we took a weekend trip to Rochelle, Illinois, to see Union Pacific Big Boy No. 4014, the largest and most powerful operating steam locomotive ... The engine is 132 feet long ...