The Illinois . . . raise Indian corn, which they have in great abundance, have squashes as large as those of France, and have a great many roots and fruits. There is fine hunting there of Wild Cattle, Bears, Stags, Turkeys, Ducks, Bustards, Pigeons, and Cranes. (Jacques Marquette, 1669) Illinois woman with some of the produce from her garden, including corn, beans, squash, and watermelon.

All human societies have economic systems for producing, obtaining, distributing, and consuming material goods and services. Economic systems are important because they allow people to adapt to their natural environment and produce the plant and animal foods they need to survive. Economic systems also involve the decisions people make about where to locate their settlements, the means people use to exchange products with other societies, and the extent to which people specialize in performing different jobs or activities.

At the time of European contact, the Illinois economy was largely self-sufficient. In the course of their yearly activities, the Illinois people produced virtually all of the foodstuffs and other material products they needed to maintain their way of life. However, the Illinois also participated in an extensive trading network. In exchange for hides, furs, and human slaves obtained from tribes living to their south and west, the Illinois traded with Great Lakes tribes and French traders for guns and other European goods. As time passed, traders and missionaries began to settle among the Illinois and their formerly self-sufficient economy became increasingly dependent upon their French allies.