Illinois is a Midwest state of USA. Illinois was formed from the Northwest Territory, which was organized in 1787. The State was originally a possession of France, who surrendered her claims to England in 1763. The first settlement was a mission at Kaskaskia, founded by Marquette in 1675. In 1679 La Salle built Fort Crevecoeur, and in 1682 established a colony at Cahokia, and in 1700 Kaskaskia was founded. George Rogers Clark, with a Virginia force, seized Cahokia and Kaskaskia in 1778, and Illinois was made a county of Virginia.