This switcher was built in 1944 by the American Locomotive Co. at Schenectady, New York for John Morrell & Co. Meat Packing as their #7. At an unknown date, it was sold to the Association of American Railroads (AAR), and assigned to their Chicago office.

#7 was donated to Mid-Continent in August 1996, when the AAR’s Chicago facility was closed. #7 was first used by Mid-Continent during Snow Train 1997. The engine normally serves as protective power for the daily steam train, as a yard switch engine, and for power when a second train is run during special events. But with all steam locomotives currently out of service for repair and restoration, #7 presently splits duty with fellow diesel #1256 in hauling all of the museum’s passenger trains.

The locomotive is powered by a McIntosh & Seymour model 539, inline 6 cylinder diesel engine. The engine develops 660 horsepower with 59,400 lbs. tractive effort at 30% adhesion. Weight on drivers is 99 tons; maximum speed is 60 mph.