fourth largest of the five Great Lakes of North America. It forms the boundary between Canada (Ontario) to the north and the United States (Michigan, Ohio, Pennsylvania, and New York) to the west, south, and east. The major axis of the lake extends from west-southwest to east-northeast for 241 mi (388 km), and the lake has a maximum width of 57 mi. The total area of the lake's drainage basin is 30,140 sq mi (78,062 sq km), exclusive of surface area, which is 9,910 sq mi. The lake's principal tributary rivers are the Detroit (carrying the discharge of Lake Huron), Huron, and Raisin rivers of Michigan; the Maumee, Portage, Sandusky, Cuyahoga, and Grand rivers of Ohio; the Cattaraugus Creek of New York; and the Grand River of Ontario. The lake discharges at its eastern end through the Niagara River, and its western end contains all of the islands, the largest being Pelee Island, Ont. With a mean surface height of 570 ft (170 m) above sea level, Erie has the smallest mean depth (62 ft) of the Great Lakes, and its deepest point is 210 ft. Because of its small size and shallow character, the lake has a comparatively short water-retention time of 2.6 years. Storms frequently cause short-period fluctuations in lake level that can amount to several feet at the ends of the lake. It is an important link in the St. Lawrence Seaway. The New York State Barge Canal has an outlet at Tonawanda, N.Y., on the Niagara River, and one of its branches enters Lake Erie at Buffalo.

Originally, a few harbours on the lake were formed by natural bays, but most of them are at the mouths of streams that were improved by protective piers, jellies, and breakwaters and by dredging to accommodate the large lake vessels. The industrial economy of the lakeshore area depends heavily upon water transportation. The important steel industry (notably, to the south at Pittsburgh and at Detroit) depends upon the movement of iron ore and limestone across the Great Lakes to Lake Erie ports (mostly to the Ohio ports of Cleveland, Ashtabula, and Conneaut). The port at Toledo, Ohio, handles soft-coal shipments, and Buffalo is an important grain port. Other prominent ports are Sandusky, Huron, Lorain, and Fairport Harbor (in Ohio), Erie (in Pennsylvania), and Port Colborne (in Ontario). Intense pollution of the lake resulted in the closing of many beaches and resorts in the 1960s, but by the late 1970s the environmental damage had begun to be arrested. Point Pelee National Park lies on the northwestern shore in southern Ontario.

The first European to see Lake Erie, when the Iroquois Indians inhabited the region, was probably the French-Canadian explorer Louis Jolliet, in 1669, although some credit the French man Étienne Brûlé with its exploration as early as 1615. The British, allied with the Iroquois, developed trade along Lake Erie in the late 17th century. British pressure led to the takeover of two strategic French forts, in 1759 (Fort-Conti, thereafter Ft. Niagara) and in 1760 (Fort-Pontchartrain-du-Détroit, thereafter Ft. Detroit). Many British loyalists then moved north of the lake into Ontario, and the American shores were not settled until after 1796. In the Battle of Lake Erie, an important engagement of the War of 1812, U.S. commodore Oliver H. Perry defeated a British squadron at Put-in-Bay, Ohio, and secured the Northwest for the United States. The lake was named after the Erie Indians who once inhabited the shores.