Map of Mississippi River, by Jacques Marquette (1673)

The map above is actually Entitled: "Carte de la decouverte faite l'an 1673 dans l'Amerique Septentrionale." Oriented with north to the right. Father Jacques Marquette (June 1, 1635 - May 18, 1675)

Father Jacques Marquette was a French Jesuit missionary and explorer. The Jesuits assigned him to New France in 1666 as a missionary to the Indigenous peoples of the Americas. He showed great proficiency in learning the local languages. He helped found missions at Sault Ste. Marie (Michigan) and at La Pointe, on Lake Superior (Wisconsin). At La Pointe he encountered members of the Illinois tribes, who told him about the important trading route of the Mississippi River. In 1673, he joined the expedition of Louis Jolliet, a French-Canadian explorer. The Joliet-Marquette expedition traveled to within 435 miles of the Gulf of Mexico but turned back at the mouth of the Arkansas River, for fear of encountering explorers or colonists from Spain. Marquette and his party returned to the Illinois Territory in late 1674, becoming the first Europeans to winter in what would become the city of Chicago. He died in 1675, at the age of 37, suffering from a bout of dysentery.

19 AUG 1687 - Engagements of Dumay and Laurent Barette to La Forest, to go to Fort St. Louis in the country of Illinois.

The Illinois Country (French: Pays des Illinois) -- sometimes referred to as Upper Louisiana (French: la Haute-Louisiane; Spanish: Alta Luisiana)

The Pays des Illinois was a vast region of New France in what is now the Midwestern United States. While these names generally referred to the entire Upper Mississippi River watershed, French colonial settlement was concentrated along the Mississippi and Illinois Rivers in what is now the U.S. states of Illinois and Missouri, with outposts in Indiana. Explored in 1673 from Green Bay to the Arkansas River by the Canadian expedition of Louis Joliet and Jacques Marquette, the area was claimed by France. It was settled primarily from the Pays d'en Haut in the context of the fur trade. The French name, Pays des Illinois, means "Land of the Illinois [plural]" and is a reference to the Illinois Confederation, a group of related Algonquian native peoples.