[5] In the late 1930s, Union Pacific (UP) appointed Otto Jabelmann as vice president of research and mechanical standards, where he and his team began building a brand-new 4-8-4 design; the FEF class, which could handle both freight and passenger service.

Union Pacific considered all FEF classes to be capable of producing between 4,000 and 5,000 drawbar horsepower.

[8][9][10] It appeared at Expo '74 in Spokane, Washington; the 1978 dedication of the Utah State Railroad Museum in Ogden, Utah;[11] the 1984 World's Fair in New Orleans; and the 50th anniversary celebration of Los Angeles Union Passenger Terminal in 1989, when it performed a side-by-side run with Southern Pacific 4449.

On February 14, 1975, it pulled Amtrak's San Francisco Zephyr from Denver, Colorado to Cheyenne, Wyoming with a pair of EMD SDP40Fs.

[12] In 1981, it traveled to the opening of the California State Railroad Museum in Sacramento, along with Union Pacific 3985, which had recently been restored to operational condition.

8444 was repainted into UP's Greyhound Scheme and was invited to an event to celebrate LAUPT's 50th anniversary along with Southern Pacific 4449, UP E9A No.

8444 raced 4449 down Cajon Pass on their respective trackage with 8444 winning by default as 4449 had to stop due to a roller bearing issue.

The "Eisenhower Centennial Special" was composed of cars from the Union Pacific, Burlington Northern and Santa Fe Railway business fleets, with additional passenger cars provided by the Norfolk Southern and Chicago and North Western railroads.

Also present in Abilene was General Eisenhower's command train, code-named "Bayonet", including the British A4 steam locomotive No.

On June 21, 1997, on the way to the National Railway Historical Society (NRHS)'s annual convention in Salt Lake City, Utah, No.

On June 24, 1999, while on display during RailFair '99, one of the 844's boiler tubes failed, and the locomotive was subsequently towed dead back to Cheyenne by the recently overhauled No.

844 teamed with Southern Pacific 4449 to pull the "Puget Sound Excursion", a round trip from Tacoma to Everett on BNSF Railway tracks.

[14] The tender was rerailed at 7:30 p.m.[14] In June 2013, the locomotive's gyrating Mars Light, installed in 1946, was removed because its mounting bolts had deteriorated.

[15] After the 2013 season, the locomotive was taken out of service for boiler work required by a change in the water treatment.

On July 12, 2016, the Union Pacific Steam Team took the locomotive on a "break-in run" as a sort of all-systems check and dress rehearsal for its return to service.

On October 13, 2016, the Union Pacific Steam Team started its 18-day "Trek To Tennessee" journey: the restored 844's first major trip.

844 made its first run on the Oregon Short Line Railroad to celebrate the 92nd anniversary of the Boise Union Pacific Depot.

Because of heavy snows and a wet spring, the trip was cut short and the engine had to run light across the Malad River because of a washed-out bridge.

In December 2018, Union Pacific requested Federal Railroad Administration (FRA) waivers to exempt UP Nos.

844, 3985, and 4014 from federal Positive Train Control (PTC) requirements;[17] in February 2019, the FRA officials responded that such waivers were not needed.

Some of those clips would be later used for the opening and closing credits of the PBS show Shining Time Station, which ran from 1989 until 1995 (including the four hour-long Family Specials).

UP 844 (and several other restored steam locomotives) appear in the music video with the Pat Metheny Group's "Last Train Home".