It is a widely accepted fact that Lake Superior, with an area of 31,820 square miles, is the world's largest freshwater lake. However, this fact is based on a historical inaccuracy in the naming of Lake Huron and Lake Michigan. What should have been considered one body of water, Lake Michigan-Huron with an area of 45,410 square miles, was mistakenly given two names, one for each lobe. The explorers in colonial times incorrectly believed each lobe to be a separate lake because of their great size.

Why should the two lakes be considered one? The Huron Lobe and the Michigan Lobe are at the same elevation and are connected by the 120-foot-deep Mackinac Strait, also at the same elevation. Lakes are separated from each other by streams and rivers. The Strait of Mackinac is not a river. It is 3.6 to 5 miles wide, wider than most lakes are long. In essence, it is just a narrowing, not a separation of the two lobes of Lake Michigan-Huron.

The flow between the two lakes can reverse. Because of the large connecting channel, the two can equalize rapidly whenever a water level imbalance occurs. Gauge records for the lakes clearly show them to have identical water level regimes and mean long-term behavior; that is, they are hydrologically considered to be one lake.

Historical names are not easily changed. The separate names for the lake are a part of history and are also legally institutionalized since Lake Michigan is treated as American and Lake Huron is bisected by the international boundary between the United States and Canada.

Of all the world's freshwater lakes, North America's Great Lakes are unique. Their five basins combine to form a single watershed with one common outlet to the ocean. The total volume of the lakes is about 5,475 cubic miles, more than 6,000 trillion gallons.

The Great Lakes are Superior, with an area of 31,820 square miles (82,414 km) shared by the United States and Canada; Huron, with an area of 23,010 square miles (59,596 sq. km) shared by the United States and Canada; Michigan, with an area of 22,400 square miles (58,016 sq. km) entirely in the United States; Erie, with an area of 9,930 square miles (25,719 km) shared by the United States and Canada; and Ontario, with an area of 7,520 square miles (19,477 km) shared by the United States and Canada.