Which Frenchman is credited with claiming the Mississippi River and its surrounding land for France?

Robert de La Salle is credited with claiming the Mississippi River and its surrounding land for France. In the late 17th century, La Salle undertook extensive exploration of North America. His most significant expedition occurred in 1682, when he traveled down the Mississippi River from its northern reaches all the way to the Gulf of Mexico. La Salle's journey culminated in his claim of the entire Mississippi River basin for France, which he named "Louisiana" in honor of King Louis XIV. This claim was pivotal in expanding French territorial interests in North America and laid the groundwork for future French colonization.

Jacques Cartier is known for his earlier explorations of the St. Lawrence River and is often associated with the French claim to Canada. Samuel de Champlain is recognized as the founder of Quebec and established relationships with Native Americans in the region but did not claim the Mississippi. Henri de Tonti was an associate of La Salle and played important roles in earlier explorations but did not make the claim himself. Thus, La Salle's expeditions are what definitively linked France to the Mississippi River and its territories.