who explored the entire mississippi to the gulf of mexico
René-Robert Cavelier, Sieur de La Salle René-Robert Cavelier, Sieur de La Salle, or Robert de La Salle (November 22, 1643 – March 19, 1687) was a French explorer. He explored the Great Lakes region of the United States and Canada, the Mississippi River, and the Gulf of Mexico. He claimed the entire Mississippi River basin for France.