Duluth, Minnesota at the western end of the Saint Lawrence Seaway, the Duluth–Superior seaport is the largest and farthest-inland freshwater seaport in North America. By far the largest and busiest on the Great Lakes, the port handles an average of 46 million short tons of cargo and over 1,100 visits each year from domestic and international vessels. With of waterfront, it is one of the leading bulk cargo ports in North America and ranks among the top 20 ports in the United States. Duluth is a major shipping port for taconite pellets, made from concentrated low-grade iron ore and destined for midwestern
The Great Lakes Group provides linehandling assistance to vessels transiting the United States Army Corps of Engineers-administered and -operated Soo Locks at Sault Ste. Marie, Michigan on the St. Mary's River, the only water connection between Lake Superior and the other Great Lakes. The Soo Locks are located in the St. Mary's Rapids, where the water falls about 21 feet from the level of Lake Superior to the level of the lower lakes. Vessels must transit the Soo Locks en route to the principal ports of Duluth, Minnesota and Thunder Bay, Ontario and outbound to the sea. In 1999 Admiral Towing and Barge Company