The Great Lakes – Superior, Michigan, Huron, Erie and Ontario – together with their connecting waterways and the St. Lawrence River outflow to the Atlantic Ocean forms the largest surface freshwater system on Earth. Covering more than 94,000 square miles and draining more than twice as much land, the Great Lakes hold an estimated six quadrillion gallons of water. The Great Lakes-St. Lawrence River drainage basin includes part or all of eight U.S. states – Minnesota, Wisconsin, Illinois, Indiana, Michigan, Ohio, Pennsylvania and New York – and the Canadian provinces of Ontario and Quebec. More than one-tenth of the population of the United States and one-quarter of the population of Canada inhabits this watershed.
The Great Lakes region contains vast forest and wilderness areas, rich agricultural lands, hundreds of tributaries and tens of thousands of smaller lakes. It has extensive mineral deposits, abundant wildlife, and a world class freshwater fishery. This binational region is North America’s industrial heartland and contains the continent’s largest hydropower production capacity. The region also has a thriving maritime transportation system and a diverse agricultural base, and it supports a multi-billion dollar outdoor recreation and tourism industry.
Great Lake Watershed from U.S. Army Corps of Engineers