Icebreakers and the U.S. Coast Guard is a great article from the Coast Guard Historian’s Office says that the origin of icebreaking in the United States came in the 1830s as side-wheel steamers with reinforced bows were found to be excellent for clearing harbor ice. This page tells the story of CG icebreaking around the country, and the Great Lakes were certainly a part of that. The Escanaba class light icebreakers in the early 20th century didn’t get the job done, but World War II made icebreaking an essential technology and led to the development of the Wind class vessels. In addition to to these four ships, a fifth was built in 1944, the icebreaker Mackinaw:
The final heavy icebreaker built during the war was the Mackinaw, a ship specifically for Great Lakes use. She was, according to Admiral Thiele, a “squashed down” Wind class vessel, with greater beam and length, but shallower draft than those vessels. Her powerplant and general design were those of the Wind class, but her hull was of mild steel, for fresh water operations. (The ocean going cutters were of high tensile steel.) This vessel was designed to extend the operating season in Great Lakes ports, a strategically important task considering the essential raw materials originating on the Lakes: iron ore, coal, limestone, etc.
In 2006, the Mackinaw was decommissioned and replaced by the new USCG Mackinaw, which we see in the picture above.
You can see more of what was involved in freeing a stuck freighter in Kathy’s Coast Guard Cutters slideshow.