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
Lake Superior National Estuarine Research Reserve county, state, and university entities. The Reserve is sponsored by the Cooperative Extension division of University of Wisconsin-Extension and hosted at the University of Wisconsin-Superior. Reserve offices and research facilities are on Barker's Island in Superior Bay, part of the Duluth-Superior harbor. The Lake Superior Reserve site represents a previously unrepresented biogeographic region within the National Estuarine Research Reserve System – the Great Lakes, Lake Superior subregion. The Lake Superior Reserve and the Old Woman Creek (Lake Erie in Ohio) are the only Great Lakes freshwater estuaries in the Reserve System. This subregion contains all of Lake Superior and its