The Union Pacific Big Boy is the largest steam locomotive ever conceived and built. There are not enough superlatives in the language to describe this locomotive. When the Big Boys were first introduced in 1941 they were the net result of all that had been learned about steam technology in the U.S. up to that time. The diesel locomotive became the main motive power for all railways in the U.S. after production of the Big Boys. There would still be more steam built for other railroads into the early 1950’s but none would surpass the Big Boy. Great Brittan, Europe and China continued to develop steam power long after the U.S. had gone to diesel, but nothing could match the size and brute horse power of the Big Boy.

Not only were these locomotives the largest ever built but they were highly successful and reliable. The Big Boy moved monumental amounts of freight during their short 18 year working career and helped win World War 2. The entire first group of Big Boys ran over 1 million miles and the last group ran over 800,000 miles. In many peoples minds no other steam locomotive in history exemplifies the zenith of the builder’s art of steam power more than a Big Boy. We are fortunate today that there is a high survival rate of Big Boys. With most famous steam locomotives that survive today we are lucky to have one example left on display or restored. In some cases many of the famous classes of locomotive have been scrapped and are now gone. The NYC Hudson and the Southern Pacific Mountain Class are two examples. Of the 25 Big Boy locomotives built 9 are still on display around the US. The locomotive numbers on the Accucraft models represent some of the surviving locomotives.