The Five Great Lakes of the United States

The Great Lakes—the world's largest freshwater system by surface area (244,000 km²)—comprise five lakes:

1. Lake Superior – Largest, deepest, coldest; 82,100 km²; max depth 406 m; borders MN, WI, MI, ON.
2. Lake Michigan – Only lake entirely in US; 58,000 km²; 281 m max; borders WI, IL, IN, MI.
3. Lake Huron – 59,600 km²; includes Georgian Bay; max 229 m; borders MI, ON.
4. Lake Erie – Smallest by volume, shallowest (64 m max); 25,700 km²; warmest; borders MI, OH, PA, NY, ON.
5. Lake Ontario – Smallest surface (19,000 km²), deep (244 m); lowest elevation; borders NY, ON; outlet to St. Lawrence.

Hydrologically, Michigan-Huron is one lake (connected by Straits of Mackinac). The system holds 22,700 km³ (6 quadrillion gallons)—21% of Earth's surface fresh water. 30M+ people depend on it for water, economy, recreation.