Superior, Lake

Largest and deepest of the Great Lakes and the largest freshwater lake in the world; area 82,100 sq km/31,700 sq mi. Extending east-west for 616 km/385 mi, it reaches a maximum width of 260 km/163 mi and depth of 407 m/1,335 ft. The lake is bordered by the Canadian province of Ontario and the US states of Minnesota, Wisconsin, and Michigan. As the westernmost of the Great Lakes, Superior is at the western end of the St Lawrence Seaway.

Duluth, Minnesota, is the largest US city on its shores, and with its sister city, Superior, Wisconsin, it is the busiest Great Lakes port, shipping grain and iron ore to the USA and Europe. Also on Lake Superior is Canada's busiest Great Lakes port, Thunder Bay, Ontario, which ships coal and grain chiefly to points in eastern Canada. Ice closes the ports from December to mid-April.

The USA has control over 54,300 sq km/20,885 sq mi of the lake, and the remaining 29,000 sq km/11,154 sq mi belongs to Canada.

Superior's chief tributary is the St Louis River, 260 km/160 mi long, which enters at Duluth. The waters discharge through St Mary's River in the southeast, flowing for 100 km/64 mi into Lake Huron; shipping proceeds through the Sault Sainte Marie Canals. Rocky cliffs mark the northern shore, some rising 300m/1,000 ft above the lake. The Keweenaw Peninsula juts from the Michigan lakeshore in the south. Many islands occur, including Isle Royale National Park and the Apostle Isles in US waters; and Michipicoten and St Ignace islands in Ontario.

The Superior region is wooded and has valuable deposits of iron ore. It is sparsely populated and the agricultural possibilities are limited. Fishing, hunting, and tourism are important to the lakeside economy, as the area remains relatively unpolluted.