Illinois, a confederation of small Algonquian-speaking North American Indian tribes originally spread over what are now southern Wisconsin and northern Illinois and parts of Missouri and Iowa. The best-known of the Illinois tribes were the Cahokia, Kaskaskia, Michigamea, Peoria, and Tamaroa.
Like other Northeast Indians, the Illinois traditionally lived in villages, their dwellings covered with rush mats and housing several families each. The Illinois economy combined agriculture with foraging; women cultivated corn (maize) and other plant foods, small parties took forest mammals and wild plants throughout the year, and most members of a given village participated in one or more winter bison hunts on the prairie. Little is known of Illinois social organization, but it was probably similar to that of the Miami, with a civil chief elected from among a village council and a war chief chosen according to his ability to lead raids.
By the middle of the 17th century, most of the Illinois people were living along the Illinois River from Starved Rock to the Mississippi, having moved there because of harassment by the Dakota Sioux, Fox, and other northern tribes. Iroquois raids greatly reduced their numbers, and the introduction of liquor by French traders further weakened the tribe. The murder of the Ottawa chief Pontiac by an Illinois individual provoked the vengeance of several northern Algonquian tribes, further reducing the Illinois population. The survivors took refuge with French settlers in Kaskaskia, while the Sauk, Fox, Kickapoo, and Potawatomi took most of the remaining Illinois territory. In 1832 the Illinois sold the lands they had retained, moving to Kansas and then to Indian Territory (present-day Oklahoma).
Early 21st-century population estimates indicated more than 1,500 individuals of Illinois descent.