Louis Jolliet was a French-Canadian explorer known for his discoveries in North America. In 1673, Jolliet and Jacques Marquette, a Jesuit Catholic priest and missionary, were the first non-Natives to explore and map the Upper Mississippi River.

Jacques Marquette, S.J., sometimes known as Père Marquette or James Marquette, was a French Jesuit missionary who founded Michigan's first European settlement, Sault Sainte Marie, and later founded Saint Ignace. In 1673, Marquette, with Louis Jolliet, an explorer born near Quebec City, was the first European to explore and map the northern portion of the Mississippi River Valley.