Union Pacific No. 4004 is a massive Articulated 4-8-8-4 "Big Boy steam locomotive built in 1941 by the American Locomotive Company (ALCO) for the Union Pacific Railroad. Designed to handle heavy freight over the Wasatch Mountains, No. 4004 was part of a fleet of 25 Big Boys built to meet the increasing demand for fast and efficient freight movement during the steam era.
After entering service, No. 4004 spent many years hauling long freight trains across the Union Pacific network. Its career came to a close in 1958, when it was retired from active service. In November of that year, the locomotive was moved into storage. Then in June 1963, it was relocated to Holiday Park in Cheyenne, Wyoming, for public display.
To move the locomotive into the park, a diesel switcher pushed 4004 along approximately 600 feet of temporary track. As a safety measure, a truck followed the locomotive, supplying air to its brake system during the move.
Over the decades on outdoor display, No. 4004 deteriorated from exposure to the elements. In response, a cosmetic restoration was completed in 2018, helping preserve the locomotive’s appearance. Since then, it has remained in relatively good condition as a static exhibit and a local landmark.
Trivia[]
- In 1958, No. 4004 was spotted doubleheading a freight train alongside fellow Big Boy No. 4013, a rare sight in the final years of steam operation.
- No. 4004 is one of three Big Boys to have a cosmetic restoration—No. 4012 in 2021 and No. 4023 in 1974.
- It was rumored that the original Hancock 3-chime whistle from No. 4004 was repurposed in 1980 for Challenger No. 3985, which had lost its own whistle following retirement, and this whistle stayed on 3985 throughout most of its excursion service until 2010. However, a 3985 stamp on the whistle during the locomotive's second restoration by the Railroading Heritage of Midwest America (RRHMA) has disproven this, and the whistle is 3985's original whistle.[1]
- No. 4004 appears side-by-side with Big Boy No. 4023 in the Herron Rail Video documentary Articulateds: America’s Biggest Steam.
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