- Great Lakes, chain of deep freshwater lakes in east-central North America comprising Lakes Superior, Michigan, Huron, Erie, and Ontario.
- Except for Lake Michigan, the lakes provide a natural border between Canada and the United States, a frontier that was stabilized by a boundary-waters treaty of 1909.
- They played a central role in the European colonization and development of North America and for decades have attracted people and industry; Lakes Erie and Ontario and the southern portion of Lake Michigan are now ringed with large population concentrations.
Physiography of Great Lakes
- The lakes drain roughly from west to east, emptying into the Atlantic Ocean through the St. Lawrence lowlands.
- Except for Lakes Michigan and Huron, which are hydrologically one lake, their altitudes drop with each lake, usually causing a progressively increasing rate of flow.
- Lake Superior, bordered by Ontario, the Upper Peninsula of Michigan, Wisconsin, and Minnesota, is the northernmost and westernmost lake and can be considered the headwater of the system. It is the deepest lake .
- Lake Michigan lies south of Lake Superior and is bordered by the Upper and Lower peninsulas of Michigan, Indiana, Illinois, and Wisconsin.
- Lake Huron lies at the same altitude as Lake Michigan and is slightly larger.
- Lake Erie is bordered by Ontario, New York, Pennsylvania, Ohio, and lower Michigan. It is the shallowest of the Great Lakes.
- Lake Ontario has the smallest surface area of the system. It has, however, the second greatest mean depth.