Niagara Falls (/naɪˈæɡrə/) is the collective name for three waterfalls that straddle the international border between Canada and the United States; more specifically, between the province of Ontario and the state of New York. They form the southern end of the Niagara Gorge.
From largest to smallest, the three waterfalls are the Horseshoe Falls, the American Falls and the Bridal Veil Falls. The Horseshoe Falls lies on the border of the United States and Canada with the American Falls entirely on the American side, separated by Goat Island. The smaller Bridal Veil Falls are also on the American side, separated from the other waterfalls by Luna Island. The international boundary line was originally drawn through Horseshoe Falls in 1819, but the boundary has long been in dispute due to natural erosion and construction.
Located on the Niagara River, which drains Lake Erie into Lake Ontario, the combined falls form the highest flow rate of any waterfall in the world that has a vertical drop of more than 165 feet (50 m). Horseshoe Falls is the most powerful waterfall in North America, as measured by vertical height and flow rate. The falls are 17 miles (27 km) north-northwest of Buffalo, New York, and 75 miles (121 km) south-southeast of Toronto, between the twin cities of Niagara Falls, Ontario, and Niagara Falls, New York.
Niagara Falls were formed when glaciers receded at the end of the Wisconsin glaciation (the last ice age), and water from the newly formed Great Lakes carved a path through the Niagara Escarpment en route to the Atlantic Ocean. While not exceptionally high, the Niagara Falls are very wide. More than six million cubic feet (168,000 m3) of water falls over the crest line every minute in high flow, and almost four million cubic feet (110,000 m3) on average.
The Niagara Falls are famed both for their beauty and as a valuable source of hydroelectric power. Balancing recreational, commercial, and industrial uses has been a challenge for the stewards of the falls since the 19th century.
The Horseshoe Falls drop about 188 feet (57 m), while the height of the American Falls varies between 70 and 100 feet (21 and 30 m) because of the presence of giant boulders at its base. The larger Horseshoe Falls are about 2,600 feet (790 m) wide, while the American Falls are 1,060 feet (320 m) wide. The distance between the American extremity of the Niagara Falls and the Canadian extremity is 3,409 feet (1,039 m).
The volume of water approaching the falls during peak flow season may sometimes be as much as 225,000 cubic feet (6,400 m3) per second. The average annual flow rate is 85,000 cubic feet (2,400 m3) per second. Since the flow is a direct function of the Lake Erie water elevation, it typically peaks in late spring or early summer. During the summer months, at least 100,000 cubic feet (2,800 m3) per second of water traverses the falls, some 90% of which goes over the Horseshoe Falls, while the balance is diverted to hydroelectric facilities. This is accomplished by employing a weir – the International Control Dam – with movable gates upstream from the Horseshoe Falls. The falls’ flow is further halved at night, and, during the low tourist season in the winter, remains a minimum of 50,000 cubic feet (1,400 m3) per second. Water diversion is regulated by the 1950 Niagara Treaty and is administered by the International Niagara Board of Control (IJC).
The verdant green colour of the water flowing over the Niagara Falls is a byproduct of the estimated 60 tonnes/minute of dissolved salts and “rock flour” (very finely ground rock) generated by the erosive force of the Niagara River itself. The current rate of erosion is approximately 1 foot (0.30 m) per year, down from a historical average of 3 feet (0.91 m) per year. It is estimated that 50,000 years from now, even at this reduced rate of erosion, the remaining 20 miles (32 km) to Lake Erie will have been undermined and the falls will cease to exist.
There are differing theories as to the origin of the name of the falls. According to Iroquoian scholar Bruce Trigger, “Niagara” is derived from the name given to a branch of the local native Neutral Confederacy, who are described as being called the “Niagagarega” people on several late-17th-century French maps of the area. According to George R. Stewart, it comes from the name of an Iroquois town called “Ongniaahra”, meaning “point of land cut in two”.
Henry Schoolcraft reported:
Niagara Falls. This name is Mohawk. It means, according to Mrs. Kerr, the neck; the term being first applied to the portage or neck of land, between lakes Erie and Ontario. By referring to Mr. Elliott’s vocabulary, (chapter xi) it will be seen that the human neck, that is, according to the concrete vocabulary, his neck, is onyara. Red Jacket pronounced the word Niagara to me, in the spring of 1820, as if written O-ne-au-ga-rah.