Calumet Harbor, artificial harbor on Lake Michigan, at the mouth of the Calumet River, NE Ill., in S Chicago. The harbor, dredged to 27 ft (8 m), is formed behind a breakwater extending c.2 mi (3.2 km) into Lake Michigan. It is a unit of the Port of Chicago and a principal terminal for shipping on the Great Lakes and the St. Lawrence Seaway. The chief products handled there were raw materials for steelmaking and iron products, but the industry has fundamentally declined. Calumet River (c.8 mi/13 km long) connects the harbor with Lake Calumet (c.2 sq mi/5 sq km) in S Chicago. Once a shallow body of water with marshy shores, the lake has been transformed into a modern deepwater port. Some heavy industry, grain-storage bins, and warehouses surround it. Canals connect the lake with the Calumet region of Indiana and with the Illinois Waterway.