Illinois Country

The Illinois Country — sometimes referred to as Upper Louisiana (; ) — was a region in what is now the Midwestern United States. The terms generally referred to the entire Upper Mississippi River watershed, though settlement was concentrated in what is now the U.S. state of Illinois, with outposts in Missouri and Indiana. Explored in 1673 from Green Bay to the Arkansas River by the Canadien expedition of Louis Joliet and Jacques Marquette, the area was claimed by France.