Niagara Falls (waterfall), waterfall in east central North America, located on the Niagara River, in western New York and southeastern Ontario. Niagara Falls consists of two cataracts: the Horseshoe, or Canadian, Falls (57 m/187 ft high), on the Canadian side of the river, and the American Falls (55 m/182 ft high), on the United States side. The waterfalls are separated by Goat Island, New York. The crestline of the crescent-shaped Horseshoe Falls, which carries about nine times more water than the U.S. cataract, is about 670 m (about 2,200 ft) long, and the fairly straight crest of the American Falls measures 328 m (1,075 ft). A small section of the American Falls near Goat Island is also known as Bridal Veil Falls. Niagara Falls was formed about 12,000 years ago, when glaciers retreated north, allowing water from Lake Erie to flow over the Niagara Escarpment, a ridge that extends in an arc across the northern Great Lakes region, from Wisconsin to New York. Erosion slowly pushed the waterfall about 11 km (about 7 mi) upstream, forming the Niagara Gorge. Before large water-diversion projects were built in the 1950s and 1960s, Horseshoe Falls was receding at a rate of more than 1 m (3 ft) per year. With reduced flows slowing erosion, it will take about 30 years for the falls to recede the distance it once did in a year. In 1954 a considerable portion of the American Falls broke off, creating a large talus, or rock slope, at the base of the cataract. In order to study ways of preventing further rockfalls and to remove some of the talus, the American Falls was successfully “shut off” for several months in 1969 by a dam that was constructed between the U.S. mainland and Goat Island. Niagara Falls is a great tourist attraction, luring millions of visitors each year. The falls may be viewed from parks located on either side of the river, from observation towers, from boats, from Goat Island, and from the Rainbow Bridge, located a short distance downstream. Visitors also may enter the Cave of the Winds, situated behind a curtain of falling water near the base of the American Falls. Samuel de Champlain, a French explorer, probably visited Niagara Falls in 1613. Father Louis Hennepin, a Flemish monk, is known to have visited the waterfall in 1678; he later published an eyewitness description of it. 
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