Niagara Falls are the main outlet of which of the Great Lakes?

As the southernmost of the Great Lakes, the majority of Lake Erie's water flows in through the Detroit River from the upper lakes — Lake Superior, Lake Michigan and Lake Huron — as well as tributaries. Lake Erie's main outlet is Niagara Falls. The Niagara River, the source of the falls, runs 36 miles (58 kilometers) and connects Lake Erie and Lake Ontario.

Lake Erie touches four U.S. states — New York, Pennsylvania, Ohio and Michigan — and the Canadian province of Ontario.

Buffalo, N.Y. (which is shown in the picture) is on the eastern end, and Toledo, Ohio, is on the western end. Cleveland, Ohio, and Erie, Pa., sit on the southern shore.

Lake Erie is the warmest of all of the Great Lakes, but it also freezes over more than the other lakes. It is the fourth largest when measured in surface area, with around 9,910 square miles (25,700 square kilometers) and the smallest by water volume, with 116 cubic miles (484 cubic km), according the Environmental Protection Agency (EPA).