The debate as to which is the largest steam locomotive ever built goes on to this day. Its always been between Union Pacific’s Big Boy and the C&O Allegheny!

The figures of weight and size are bounced around by who ever happens to feel the need! How can a 4-8-8-4 weigh less then a 2-6-6-6? The answer may come from the fact that the Allegheny’s boiler is a bit larger then the Big Boy! The listed figure of weight on the Allegheny is 724,500 lbs however this figure goes as high as 778,000 lbs on engines 1600-1609 for the 1941 Lima built locomotives. The general published weight on the Big Boy is 772,250 lbs. This debate will continue for years to come because if it hasn’t been solved in almost 70 years it never will be. That being said the Allegheny is one handsome and impressive machine! The term super power used by the Lima Locomotive Works fits this locomotive ,and with 7,498 horsepower as compared to 6,900 for the Big Boy the race for the biggest and most powerful starts to lean toward the Allegheny. However the jury is still out on this subject, and its safe to say that both machines were awesome, and that they will always represent the pinnacle of steam locomotive development in North America.