Return of a Rail Icon: Big Boy 4014 Steams Through Colorado

Union Pacific 4014 Echo Utah, CC BY 2.0, via Wikimedia Commons

There’s something undeniably captivating about the sight and sound of a steam locomotive, and few are more awe-inspiring than Union Pacific’s Big Boy 4014. This colossal steam engine -the world’s largest operating steam locomotive and a 1940s masterpiece of American engineering - is once again capturing the imagination of railway enthusiasts and curious onlookers alike, as it thunders through the breath-taking landscapes of Colorado on one of its rare excursions.

 Marvel of Engineering
Big Boy 4014 is one of the largest and most powerful steam locomotives ever built. Originally constructed in 1941 by the American Locomotive Company (ALCO), it was designed to haul heavy freight loads over the unforgiving and steep mountain grades of the American West across the Wasatch Mountains between Utah and Wyoming. Weighing in at over 1.2 million pounds (around 540 tonnes) and stretching more than 132 feet long, this locomotive is a remarkable feat of engineering; a moving monument to industrial ambition. Only 25 Big Boys were ever built, and No. 4014 is one of only eight of these magnificent locomotives remaining, and the sole survivor still in operation today. After decades of retirement, it was painstakingly restored by Union Pacific’s heritage fleet team and returned to active service in 2019, traveling the country on special tours, rekindling the romance of steam travel and turning heads wherever it goes.

Bigboy 4014 making a whistle stop at Kimball, Nebraska, CC BY-SA 4.0, via Wikimedia Commons

The Nostalgia of Steam Travel
Colorado’s dramatic landscapes and historic railways make it the perfect stage for Big Boy’s appearances. When 4014 rolls into American towns like Denver, Pueblo, or Trinidad, it’s more than just a train ride - it’s an event! Locals and tourists line the tracks, cameras in hand, eager to witness the power and nostalgia of steam rail travel reborn. The locomotive’s visit is often part of Union Pacific’s ‘Great Race’ tours, designed to celebrate American rail heritage and inspire a new generation of railway lovers. During these tours, Big Boy stops at key locations, allowing visitors to get a close look, chat with crew members, and learn more about the history of this steam-powered giant.

The Sound of Power
There’s no mistaking Big Boy’s approach. The deep, rhythmic chuff of its pistons, the scream of its whistle, and the ground-shaking rumble of its 68-inch drive wheels combine to create a sensory experience like no other. Whether you’re a seasoned railfan or simply someone who appreciates historic craftsmanship, seeing 4014 in action is unforgettable.

Preserving the Past, Inspiring the Future
Big Boy 4014 is more than a machine; it’s a living piece of history. Its restoration and operation serve as a reminder of the United States’ pivotal role in railway innovation, and of the thousands of workers who built and operated these machines. For Colorado, a state with a rich railroad legacy, the presence of 4014 is a source of pride and wonder. Colorado’s dramatic scenery, historic rail towns and rich railway heritage make it the perfect backdrop for Big Boy’s grand appearances. From the mile-high city of Denver, through the charming streets of Pueblo, to the foothills near Trinidad, Big Boy’s route showcases the very best of the American West.

To make the most of Big Boy's recently announced operational route for September 2025 we have now confirmed the 2025 dates of our popular Colorado escorted tour! Our Colorado itinerary covers the dramatic scenery of the American West, the wonderful main line Amtrak California Zephyr, impressive narrow gauge tourist steam rail lines like Durango Silverton, Cumbres Toltec, Pikes Peak Cog Rail and, of course, the Big Boy 4014 in action! Not to mention friendly people, fabulous accommodation and really good food. This is as close as you’ll get to the perfect holiday! We run this tour with a small party of up to 6 people only and thus have a limited availability. For full information and to book, click here. Or get in touch.

4014 Accelerates East, CC BY-SA 4.0, via Wikimedia Commons