Engine No. 9 pulled the last train out of Breckenridge in 1937, when the narrow-gauge line over Boreas Pass shut down for good. Built in 1884 by Cooke Locomotive and Machine Works of Paterson, New Jersey — one of only eight of its kind ever produced — it hauled passengers, ore and goods on the Denver, South Park & Pacific 'High Line,' which crossed the Continental Divide at 11,493 feet, then the highest railroad pass in the nation.

After stints at the 1939 New York World's Fair, the Black Hills and the Georgetown Loop, the Heritage Alliance brought the locomotive home on December 13, 2010, setting it down less than 100 feet from its original tracks.

The park surrounds No. 9 with a box car exhibit, a loaded flat car, a caboose, a rotary snowplow nearly identical to the one that kept the line open in winter, a small railroad museum and a railroad-themed playground. Outdoor exhibits are free and open around the clock; guided tours run in summer.