It pulled Southern's highest-level passenger trains from 1926 until Dieselization in the early 1950s, mostly on Southern's Charlotte Division. Its most famous and historic use was as one of the locomotives that pulled President Franklin Roosevelt's funeral train from Warm Springs, Georgia, to Washington in April 1945. The Smithsonian Institution gathered information on two of 1401's engineers from a 1962 Greenville, SC newspaper interview with one of the Southern's fireman nicknamed "Box Car". "Box Car" (fireman for "DC") accidentally confused the engineers, who happened to be brothers. Oscar "OC" Surratt was one of the engineers on the train that took Roosevelt to Warm Springs. His brother Cleve "DC" Surratt was one of the engineers that brought Roosevelt's body back to Washington. In the 1950s, war hero and outside legal counsel to Southern Graham Claytor (who would later become Southern's president) convinced then-Southern president Harry deButts to donate one of the retired Ps-4s to the Smithsonian instead of scrapping it. In this way 1401 was saved, and has been on display at the Smithsonian since the early 1960s.
Today Southern Railway 1401 is one of the attractions at the Smithsonian Institution in Washington, D.C. Southern cosmetically restored the locomotive just before sending it for display at the Smithsonian, and it was probably stored serviceable when it was retired from active service, but it has not operated in more than half a century. When Graham Claytor was a Southern executive in the mid-1960s, he attempted to lease 1401 from the Smithsonian for operational use in Southern's steam excursion program. The Smithsonian refused, and Claytor leased Southern Railway 4501 (originally a freight locomotive with a 2-8-2 wheel arrangement) and painted it in the green, gold, and silver scheme instituted for the Ps-4s. Accordingly, it seems unlikely that 1401 will ever steam again. However it is believed to have been in good condition when retired, and has spent most of the time since inside, it is probably in relatively good internal and mechanical condition. Cosmetically, it is in excellent shape. In 2012, the locomotive made an appearance in an episode of Parks and Recreation.