The Milwaukee Road's first large order for 4-8-4s went to Baldwin Locomotive Works in 1937 for 40 class S2 Northern types. These locomotives featured a General Steel Castings one-piece cast steel bed, and sported Boxpok drivers of generous 74-inch diameter although they operated principally in freight service. All locomotive axles had roller bearings. Their cylinder dimensions were 26x32 inches, and they mustered a boiler pressure of 285 p.s.i. With these specifications they produced 70,816 pounds of tractive effort and weighed 490,450 pounds. Having a grate area of 106 square feet, they boasted an evaporative heating surface of 5509 square feet and a superheating surface of 2336 square feet. No. 206 represents the S2 class in this Baldwin builder's photo; it was dropped from the roster in 1956.