The last steam locomotives erected by the American Locomotive Company for service in the United States were the seven 2-8-4s of class A2a delivered to the Pittsburgh & Lake Erie in 1948. No. 9405, shown above at an unidentified location, is our representative of this class. These powerful engines developed a tractive effort of 67,300 pounds, but lacked boosters. Whereas most modern Berkshire type locomotives had a driver diameter of 69 inches, the A2s rolled on 63-inch drivers more suitable for their duties on the P&LE, which served the steel industry and had heavy coal and ore traffic. They had 26x32-inch cylinders and a boiler pressure of 230 pounds per square inch, and weighed in at a hefty 436,000 pounds. Their grate area measured 95 square feet, and they were equipped with overfire jets, visible along the side of No. 9405's firebox, which improved fuel combustion by increasing the air supply. Strangely, despite their advanced design, the A2s were delivered with traditional spoked drivers instead of the more modern disc drivers. They were painted a deep olive green color which eventually faded to black under the gritty conditions of the industrialized areas in which they operated.

By the time the P&LE Berkshires entered service, dieselization was already advancing across the New York Central System, beginning in the East. As newer steam power was displaced it was being moved westward. By the early 1950s the A2s had been withdrawn from service on the Pittsburgh & Lake Erie and transferred to former "Big Four" lines in Ohio and Indiana, where they may be seen in the Herron video New York Central, Volume 2. According to one report, they may also have seen service on the Mackinaw City line in Michigan. Within a few years they were scrapped, having known one of the shortest life spans of any steam locomotive of modern design.