Hernando de Soto was the first European explorer to discover the Mississippi River.

In 1541, Hernando de Soto, a Spanish explorer, became the first European to discover the Mississippi River during his expedition across the southeastern United States. This journey was pivotal in the exploration of North America, as he interacted with numerous Indigenous tribes along the river. De Soto's findings enhanced European knowledge of the region's geography and resources, paving the way for subsequent exploration and colonization efforts in the Mississippi River Basin.