Which Great Lake is the source of the Niagara River?

Lake Erie is the source of the Niagara River.

The river flows north from the eastern end of Lake Erie for about 58 kilometres before entering Lake Ontario. Along the way, it passes over Niagara Falls, one of the world’s best-known waterfalls. The river therefore forms a major link between the fourth and fifth Great Lakes in the usual west-to-east chain.

The Niagara River also forms part of the international boundary between Ontario and New York. Its flow is regulated for hydroelectric power and other purposes, while a portion of the water is diverted through canals and power facilities.

A frequent mix-up is to say that Niagara Falls connects Lake Erie directly to the Atlantic Ocean. It does not: the river first carries water into Lake Ontario, then the St. Lawrence River transports it downstream toward the Atlantic.