The Great Lakes

The Great Lakes - Superior, Michigan, Huron, Erie and Ontario - are a dominant part of the physical and cultural heritage of North America. Shared with Canada and spanning more than 750 miles (1,200 kilometers) from west to east, these vast inland freshwater seas have provided water for consumption, transportation, power, recreation and a host of other uses.

http://www.epa.gov/glnpo/basicinfo.html