One of the World’s Largest Steam Locomotives Returns to the Tracks

Six decades after the last "Big Boy" retired, Union Pacific is rebuilding the famous locomotive.

big boy
Colorado & Southern Railway Co. Road master, looks on while Tony Leo cuts a twisted rail Monday in front of "Big Boy," the world's biggest railroad steam engine. (Duane Howell/The Denver Post via Getty Images)
Denver Post via Getty Images

Seventy years after the first Transcontinental Railroad was completed, the Union Pacific, one of the biggest railroad companies in America, was still struggling to move heavy freight trains over the Rocky Mountains, and would have to use multiple locomotives to ascend the high passes. This required more time, workers, and fuel. So in 1940, the Union Pacific’s mechanical engineers teamed up with the American Locomotive Company to build one of the world’s largest steam locomotives. They named it “Big Boy,” writes Atlas Obscura. 

Six decades after the last Big Boy was taken off the rails, the Union Pacific is rebuilding one of the famous locomotives in honor of the upcoming sesquicentennial celebration of the first Transcontinental Railroad. Ed Dickens Jr, a Union Pacific steam locomotive engineer and the man leading the rebuild, has said that rebuilding the locomotive is like trying to resurrect a Tyrannosaurus rex.

The Big Boy was just that: big. If you stood it on its end, it would be the equivalent of a 13-story building. It weighed more than one million pounds and was 132 feet, 9 inches long. Each one cost about $265,000 to build, which is about $4.4 million today. Union Pacific bought 25 of the Big Boys between 1941 and 1944. They were used until about 1959, when they were replaced with diesel-electric locomotives.

“I cannot think of a bigger way to celebrate this anniversary than restoring a Big Boy locomotive,” said historian John E. Bush, a self-described “Union Pacific steam locomotive nut” and author of numerous train books and a Trains Magazine blog about the locomotives, to Atlas Obscura. “This is something railroad enthusiasts have dreamed about for more than a half-century.”

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