Legendary 'Big Boy' Train Is Making A Big Return In 2026

Almost every little boy, and of course some little girls, go through a train phase at some point during childhood. There's just something about trains, especially the steam engines of bygone years. The steady chugging sounds, the way they move across a track, and that sense of adventure captivate many. Some children eventually outgrow their interest in trains, but many don't. Tourist railroads and steam excursions are very popular and now, some lucky steam aficionados may get to experience the world's largest operating steam locomotive — the Big Boy.

Of the eight Big Boy locomotives that live on today, only number 4014 is still in operation. These steam engines, which were built to move heavy equipment during World War II, are absolute behemoths. No. 4014 retired in 1961 and spent decades as a museum piece before being restored to service in 2019. Running limitations due to its size have kept it mainly in the Midwest and on the West coast, but now the Big Boy is embarking on an historic cross-country operation.

To celebrate America's 250 anniversary this year, Union Pacific, which owns Big Boy No. 4014, announced that it will take its first coast-to-coast tour, making stops that celebrate "where we came from and where we are headed." At the time of writing, the company had not yet disclosed a schedule, but trainspotters can keep an eye on its website. The 1.2 million-pound engine is somewhat limited due to its immense size. Some tracks and bridges can't hold its weight, and despite its articulated design, some curves are just too tight for its 31-foot length.

Big Boy No. 4014 was one of 25 such engines that were commissioned by Union Pacific to help with the war effort. They have a 4-8-8-4 wheel arrangement, which means they have four pilot or leading wheels in front, two sets of eight driving wheels, and four wheels in the rear. Because these engines are so long, the frames are articulated, or hinged, to help them get around narrow curves. These locomotives were built specifically to move freight over the steep Wasatch Mountain Range in Utah and across Wyoming. They could do the work of three smaller steam engines, pulling up to 120 freight cars at 40 mph.

Only eight of these massive engines survive today, and 4014 is the only one in running condition. The other seven are on display in museums across the country. After No. 4014 was retired in 1961, she ended up at the RailGiants Train Museum in Pomona, California. Many steam engines that land in museums are never again operational, but luckily, RailGiants had the foresight to maintain No. 4014 with the help of grants from companies like ExxonMobil and Boeing. It was no small feat — this giant engine requires giant tools, and employees often had to borrow equipment used in other industries. Union Pacific, which never fully abandoned steam, acquired No. 4014 from the museum in 2013.

In July 2013, Union Pacific announced plans to restore Big Boy No. 4014, something that many steam fans thought they'd never see. Before settling on 4014, Union Pacific toured the country to take a look at the remaining eight locomotives to determine which would be the best choice for restoration. Finally, they settled on No. 4014 due to the museum's dedication in maintaining the huge locomotive, which included lubricating its running gear for decades.

It took a team of nine full-time employees more than two years to restore No. 4014. Its boiler was less corroded than the other surviving locomotives, but it was still a massive job. The shop in Cheyenne, Wyoming where it was restored had long ago been converted for newer diesel locomotives, so it had to be reconfigured. The team also had to locate or remanufacture many of the original tools needed for the Big Boy locomotives, and many parts were made from scratch rather than restored, for the sake of safety.

The Big Boy was originally a coal-burning engine, but the locomotive required massive amounts of coal (and water), eating through the supply carried in the tender in about two hours. In order to be able to make longer excursions, the restoration team converted the system to burn oil instead. And in a truly modern twist, you can track 4014's current location, and join Union Pacific's Steam Club to get the latest news and scheduling information.