Illinois Territory

Illinois Territory Soundex Code I452

The Illinois Territory was an organized incorporated territory of the United States that existed from Wednesday, March 1, 1809, until Thursday, December 3, 1818, when the southern portion of the territory was admitted to the Union as the State of Illinois. Its capital was the former French village of Kaskaskia, Illinois. The area was earlier known as "Illinois Country" while under French control, first as part of French Canada and then as part of French Louisiana. The British gained authority over the region with the 1763 Treaty of Paris, marking the end of the French and Indian War. During the American Revolutionary War, Colonel George Rogers Clark took possession of the entire Illinois Country for Virginia, which established the "County of Illinois" to exercise nominal governance over the area. Virginia later ceded nearly all of its claims to land north of the Ohio River to the Federal government of the United States in order to satisfy objections of land-locked states. The area became part of the United States' Northwest Territory (from Friday, July 13, 1787 until Friday, July 4, 1800), and then part of the Indiana Territory as Ohio prepared to become a state. On Friday, February 3, 1809, the 10th United States Congress passed legislation establishing the Illinois Territory, after Congress received petitions from residents in the far western areas complaining of the difficulties of participating in territorial affairs in Indiana.