Illinois Country

The Illinois Country "', i.e. the Illinois people) — sometimes referred to as Upper Louisiana — was a vast region of New France claimed in the 1600s 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 Canadien expedition of Louis Jolliet 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. Over time, the fur trade took some French to the far reaches of the Rocky Mountains, especially along the branches of the broad Missouri River valley. The French name, Pays des Ilinois, means "Land of the Illinois [plural]" and is a reference to the Illinois Confederation, a group of related Algonquian native peoples.

Up until 1717, the Illinois Country was governed by the French province of Canada, but by order of King Louis XV, the Illinois Country was annexed to the French province of Louisiana, with the northeastern administrative border being somewhat vaguely on or near the upper Illinois River. The territory thus became known as "Upper Louisiana." By the mid-18th century, the major settlements included Cahokia, Kaskaskia, Chartres, Saint Philippe, and Prairie du Rocher, all on the east side of the Mississippi in present-day Illinois; and Ste. Genevieve across the river in Missouri, as well as Fort Vincennes in what is now Indiana.

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