Neptune's Needle

The Great Lakes, group of five freshwater lakes, central N. Amer., creating a natural border between the U.S. and Canada and forming the largest body of freshwater in the world, with a combined surface area of c.95,000 sq mi/246,050 sq km. From W to E they are Lakes Superior, Michigan, Huron, Erie, and Ontario, out of which flows the Saint Lawrence R. The distance from Duluth, Minn., at the W end of L. Superior, to the outlet of L. Ontario is 1,160 mi/1,867 km. The international boundary passes approximately through the center of all the lakes except L. Michigan, which lies entirely within the U.S.

The Great Lakes were formed approximately at the end of the Pleistocene period, when the glacier-carved lake basins were filled with meltwater from the retreating ice sheet. The lakes are connected to each other by straits, short rivers, and canals. The ht. above sea level of the lake surfaces varies from L. Superior’s 602 ft/183 m to L. Ontario’s 246 ft/75 m; the greatest sudden drop occurs at Niagara Falls (167 ft/51 m) between lakes Erie and Ontario. All the lake bottoms, except that of L. Erie, extend below sea level. French traders were the first Europeans to see any of the Great Lakes (referred to them as "the sweetwater seas"); Etienne Brule visited L. Huron c.1612. In 1614, Brule and French explorer Samuel de Champlain explored L. Huron and L. Ontario. In 1679, French explorer Robert LaSalle sailed from L. Erie to L. Michigan. The Great Lakes region, rich in furs, was contested for many years by the French, English, and Americans. The close of the War of 1812 finally ended the struggle for possession of the Great Lakes, and settlement of the region rapidly followed.

The opening of the Erie Canal in 1825 accelerated the development of commerce on the Great Lakes, which carry large quantities of iron ore and grain, coal, and petroleum, and manufactured articles from April until Dec., until ice closes most of the ports and winter storms hinder navigation. Large concentrations of population and industry along the lakes’ shores have led to increasing pollution, especially of L. Erie. The large industrial lakefront cities include Toronto, Hamilton, Buffalo, Cleveland, Detroit, Gary, Milwaukee, and Chicago. The opening of the St. Lawrence Seaway in 1959 made the Great Lakes a truly international body of water. The Illinois Waterway connects the lakes with the Mississippi R. and the Gulf of Mexico; the N.Y. State Barge Canal joins the Great Lakes with the Hudson R. and the Atlantic Ocean. The Great Lakes region, with its natl. parks and lakeshores, state parks, and many natural and scenic features, has become an important year-round recreation area.

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Peter Richards