The Lackawanna was one of the first US railroads to adopt the 4-8-4 wheel arrangement. In contrast to the Northern Pacific, these were not called “Northern” here, but “Poconos”. They were seen here as the successor to the 4-8-2 with a larger firebox. Thanks to thermic siphons and arch tubes, they came up with a firebox heating surface of 493 square feet. With a driver diameter of 77 inches, they were clearly intended for express trains, while a diameter of only 73 inches was chosen at the Northern Pacific. The later Poconos of the Lackawanna also had smaller wheels.