lake regarded as the main source of the Mississippi River, in Clearwater county, northwestern Minnesota, U.S. The lake, of glacial origin, covers an area of 1.7 square miles (4.4 square km) and has a maximum depth of 40 feet (12 metres). From the lake's surface, which is 1,475 feet (450 metres) above sea level, the Mississippi flows southward 2,350 miles (3,780 km) to the Gulf of Mexico (Mexico, Gulf of).

The fur trader William Morrison may have been the first white man to visit the lake in 1803 or 1804. It was explorer and ethnologist Henry Rowe Schoolcraft (Schoolcraft, Henry Rowe), however, who proposed Lake Itasca as the true source of the Mississippi in 1832. French explorer Joseph Nicollet (Nicollet, Joseph Nicolas) surveyed the area in 1836 and confirmed Schoolcraft's claim. Some geologists, however, have believed that other glacial lakes in the region also supply the headwaters of the river.

Schoolcraft is generally credited with having coined the name Itasca from the Latin words veritas (“truth”) and caput (“head”). Native American legend, however, mentions I-tesk-ka, the daughter of Hiawatha, whose tears of anguish at being spirited away to the netherworld reputedly formed the source of the Mississippi.

The 50-square-mile (130-square-km) Itasca State Park was established around the Itasca basin in 1891. The lake is stocked with game fish and is popular with boaters.