The Norfolk and Western Railway (N&W) built it in 1942 at its own Shops in Roanoke, Virginia as the second member of the N&W's Y6a class.

2156 was retired from revenue service in July 1959, and it is now owned by the National Museum of Transportation in St. Louis, Missouri.

Throughout the 1930s, the Norfolk and Western Railway's (N&W) mechanical engineering team explored numerous ways to refine the Y series 2-8-8-2 compound mallets, since the public demand for coal was increasing, despite the effects of the Great Depression.

[3][4] The N&W quickly decided to further develop the Y5 design to improve it, so from September 1936 to November 1940, they turned out thirty-five locomotives of the Y6 class (Nos.

[5][6] The Y6s shared identical specifications to the Y5s, but with major design changes for improved efficiency; they were built with cast steel frames connected by a pin hinge; outside frame bearings on their pilot and trailing trucks; roller bearings for all the wheel journals; and automatic lubricators.

[11] Most of the N&W's routes consisted of multiple steep grades, where the amount of cars a Y6a was allowed to pull was limited, and a pusher was required for assistance.

[10][11] In 1955 and 1956, after the N&W realized the economic challenges of keeping an all-steam roster, the railway decided to order some RS-11 locomotives from ALCO and GP9s from EMD to dieselize two of their eastern divisions.

[12] In early April 1958, Stuart T. Saunders succeeded Robert H. Smith as president of the N&W, and the former made the decision to completely dieselize the N&W railway, with several additional GP9s quickly being ordered.

2156 was retired from service, the N&W donated the Y6a to the National Museum of Transportation (MoT) in Kirkwood, Missouri, with Stuart Saunders personally presenting it at a dedication ceremony.

[20][21] Norfolk Southern (NS) facilitated the transaction, and the railroad being tasked to cosmetically restore the MoT's EMD DDA40X No.

[23] It was first transferred by the St. Louis Terminal Railroad over the Union Pacific mainline from the MoT interchange in Kirkwood, to East St.

2156, along with some passenger coaches, through Decatur, Illinois, Fort Wayne, Indiana, and Bellevue, Ohio, before the remainder of the move occurred over former N&W rails.

[25][26] In January 2020, the VMT began negotiations with the MoT to either extend the five-year lease or outright purchase No.