information:extraction
Statistics

The Great Lakes contain 21% of the world's surface fresh water: 5,472 cubic miles (22,810 km), or 6.0×10 U.S. gallons, that is 6 quadrillion U.S. gallons, (2.3×10 liters). The lakes contain about 84% of the surface freshwater of North America; if the water were evenly distributed over the entire continent's land area, it would reach a depth of 5 feet (1.5 meters). This is enough water to cover the 48 contiguous U.S. states to a uniform depth of 9.5 feet (2.9 m). Although the lakes contain a large percentage of the world's fresh water, the Great Lakes supply only a small portion of U.S. drinking water on a national basis.

The total surface area of the lakes is approximately 94,250 square miles (244,100 km) —nearly the same size as the United Kingdom, and larger than the U.S. states of New York, New Jersey, Connecticut, Rhode Island, Massachusetts, Vermont, and New Hampshire combined. The Great Lakes coast measures approximately 10,500 miles (16,900 km), but the length of a coastline is impossible to measure exactly. Canada borders approximately 5,200 miles (8,400 km) of coastline, while the remaining 5,300 miles (8,500 km) are bordered by the United States. Michigan has the longest shoreline of the United States, bordering roughly 3,288 miles (5,292 km) of lakes, followed by Wisconsin (820 miles (1,320 km)), New York (473 miles (761 km)), and Ohio (312 miles (502 km)). Traversing the shoreline of all the lakes would cover a distance roughly equivalent to travelling half-way around the world at the equator.

A notable modern phenomenon is the formation of ice volcanoes over the lakes during wintertime. Storm-generated waves carve the lakes' ice sheet and create conical mounds through the eruption of water and slush. The process is only well-documented in the Great Lakes, and has been credited with sparing the southern shorelines from worse rocky erosion.