The Niagara River is about 58 kilometres (36 miles) in length and is the natural outlet from Lake Erie to Lake Ontario. The elevation between the two lakes is about 99 metres (326 feet), half occurring at the Falls themselves. The total area drained by the Niagara River is approximately 684,000 square kilometres (264,000 square miles) and more than 168,000 cubic metres (6 million cubic feet) of water go over the crestline of Niagara Falls every minute.