Challenger #3985 is an active member of the Union Pacific Railroad Heritage Fleet, a group of older locomotives that are maintained in operating condition. In this photo, #3985 was pulling a fall colors tour through Saint Paul, Minnesota in September, 2008.

This locomotive was built by the American Locomotive Company in 1943 as part of an order of 105 Challengers for the Union Pacific. #3985 was in front-line service until 1957. She was retired and placed in storage in 1962. In 1975, she was moved to the Cheyenne Depot to be put on public display. A group of Union Pacific employees worked to restore the locomotive to running condition in 1981. In 1990, she was converted from coal to burn a heavy bunker oil. When #3985 is not out pulling tourist trains, she is housed in Cheyenne, Wyoming. #3985 is the largest and most powerful steam locomotive in operation in the world at this time.