Louis Jolliet

Louis Jolliet (September 21, 1645last seen May 1700) was a French-Canadian explorer. He was known for his discoveries in North America. Jolliet and Jesuit Father Jacques Marquette, a Catholic priest and missionary, were the first non-Natives to explore and map the Mississippi River in 1673. 
This journey would lead them to present-day Chicago River and discovered an area near a portage which would later be known as Chicago.