Set at the crossroads of the nation, Cheyenne has long been a pivotal hub in America’s rail network. Historically, Cheyenne served as an essential stop for locomotives to refuel before tackling the daunting Rocky Mountains. More than just a pit stop though, Cheyenne became a crucial repair stop for trains, making it indispensable on the transcontinental rail line.  

What Is the World’s Largest Steam Locomotive?

Close-up view of the world’s biggest train engine, Union Pacific Big Boy 4014, in Cheyenne, WY.

Cheyenne is a special place for train lovers for many reasons, but one is that we house not one, but two of the handful of remaining Big Boy Steam Engines. The Big Boy steam engines are still to this day the world’s largest steam locomotive ever made. 


What are the Union Pacific Big Boys?

Between 1941 and 1944, there were 25 Union Pacific Big Boy Locomotives made. Each Big Boy was approximately 132 feet in length and weighed upwards of 1.2 million pounds, making them the largest steam locomotives in the world. They were primarily used for hauling freight over the mountains during World War II, contributing significantly to the war effort and the economic expansion of the post war effort. 


Why was the Big Boy Steam Locomotive important?

Big Boys were created at a pivotal time, as their size and power allowed them to haul trains weighing over 4,000 tons at speeds up to 80 miles per hour. Despite their size and power, they were known for their smooth ride and ability to maintain high speeds over long distances. Big Boys were also incredibly agile for their size which helped them negotiate tricky curves.


Big Boy Locomotive versus Diesel Locomotive

Engineer waving from the cab of the world's biggest train engine, Union Pacific 4014, with steam rising around it.

Big Boy is a sight to be seen, at an incredible 132 feet in length. Comparatively, a standard Union Pacific diesel locomotive is only 74 feet long. 

Big Boy Locomotive Stats

Tender type: 14-wheeled
Water Capacity: 25,000 gallons
Originally Coal Fueled, with 56,000 lb. capacity. Now converted to No. 5 Oil.
Maximum Tractive Power: 135,375 lbs.

Where can I see the Union Pacific Big Boy steam locomotive?

Out of the 25 original Big Boy locomotives, there are only 7 remaining that are static displays, and one that has been restored and tours the nation. 

  1. Cheyenne, Wyoming: Big Boy #4014 (touring) & Big Boy #4004 (static)
  2. St. Louis, Missouri: Big Boy #4006
  3. Dallas, Texas: Big Boy #4018
  4. Omaha, Nebraska: Big Boy #4023
  5. Denver, Colorado: Big Boy #4005
  6. Scranton, Pennsylvania: Big Boy #4012
  7. Green Bay, Wisconsin: Big Boy #4017

Can I get a tour of the Union Pacific Big By?

Tourists observing the Union Pacific Big Boy 4014, the world's biggest train engine.

You can always visit Big Boy #4004 in Holliday Park in Cheyenne, however, a few times a year the Union Pacific Steam Shop and RoundHouse does open up for tours. Tours sell out quickly, so be sure to stay up to date! Also, check out the Cheyenne Depot Museum popular Depot Days where you can learn about this amazing locomotive in-person.


Is the Union Pacific Big Boy Steam Locomotive still running today?

Out of the 25 Big Boy Steam Engines that were built, there is only one that is still operational. Big Boy 4014 was reacquired by Union Pacific in 2014, and between 2014 and 2019 was restored and brought back to life just in time for the 150th anniversary of the first transcontinental railroad. 


2024 Schedule: Big Boy 4014

Union Pacific Big Boy 4014 steam locomotive charging through a field with a thick plume of steam, adorned with American and Union Pacific flags.

Photo Credit @denisewyo

Big Boy #4014 will embark on its Westward Bound Tour this summer! Kicking off on June 30th, Big Boy will leave home and head to Roseville, CA, and will return back by the end of July. Mark your calendars for public displays in Roseville on July 12th-13th and in Ogden, UT on July 20th-21st. 


Come See the World’s Largest Steam Locomotive

Union Pacific and Big Boy #4004 and Big Boy #4014 both remain important to the history and heritage of Cheyenne, as well as a great reason for any train lover to visit!