The fourth largest of the five Great Lakes of North America. It is the southernmost, shallowest, and smallest by volume of the Great Lakes and therefore also has the shortest average water residence time. It forms the boundary between Canada (Ontario) to the north and the United States (Michigan, Ohio, Pennsylvania, and New York) to the west, south, and east. The major axis of the lake extends from west-southwest to east-northeast for 241 mi (388 km), and the lake has a maximum width of 57 mi. The total area of the lake's drainage basin is 30,140 sq mi (78,062 sq km), exclusive of surface area, which is 9,910 sq mi.