Niagara

Niagara, river, east central North America, in western New York and south-eastern Ontario, forming part of the United States-Canadian boundary. About 55 km (34 mi) long, it issues from Lake Erie at Buffalo, New York, and flows north to Lake Ontario. Near its head the river divides into two channels, between which lies Grand Island, New York. The channels merge just beyond the island, and the river soon passes over Niagara Falls. The Whirlpool Rapids are a few miles north of the cataract. During its course the Niagara, which is the main drainage outlet of the four upper Great Lakes, makes a descent of about 99 m (326 ft), about one-half of which occurs at the waterfall. The river is navigable except in the region of the waterfall and rapids.