Answer:
Robert de La Salle explored the Mississippi River and built trading posts on it.
Step-by-step explanation:
Rene Robert Cavelier de La Salle was a French explorer, famous for his incursions into North America, where he toured the region of the Great Lakes of the United States and Canada, and then the Mississippi River, exploring the territories located between the Saint Lawrence River valley and the Mississippi delta, claiming those territories for France.