In 1911 Soo Line and its Wisconsin Central subsidiary began manufacturing a series of Pacifics ranging from the H-3 to the H-23 of 1923. It started with eleven H-3s and ten H-21s, which differed almost only in the boilers of different sizes. Like their successors, they had cylinders measuring 25 by 26 inches and 75-inch wheels. Initial boiler pressure of 185 psi was soon increased to 200 psi. Three H-3s and one H-21 still exist today.

In 1914 four examples of the H-22 class were added, which already had a slightly smaller boiler with a pressure of 200 psi. It was not until 1923 that six examples of the H-23 class followed, which essentially corresponded to the H-22. These were retired by 1959. Numbers 2718 and 2719 still exist today. 2718 is now in Green Bay, Wisconsin and 2719 was serviceable for a long time until the boiler deadline of 2013.