|Territory of Illinois|
|Organized incorporated territory of the United States|
|• Type||Organized incorporated territory|
• Established by Congress
|March 1 1809|
• Military Tract of 1812 created in western Illinois
|May 6, 1812|
• Granted statehood
|December 3 1818|
The Territory of Illinois was an organized incorporated territory of the United States that existed from March 1, 1809, until 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 (which is still a part of the State of Illinois, but is now accessible only from Missouri, as it now lies west of the Mississippi River).
The area was earlier known as "Illinois Country" while under French control, first as part of French Canada and then its southern region as part of French Louisiana. The British gained authority over the region east of the Mississippi River from the French, 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 region for Virginia, which established the "County of Illinois" to exercise nominal governance over the area. Virginia later (1784) ceded nearly all of its land claims north of the Ohio River to the Federal government of the United States.
The area became part of the United States' Northwest Territory (from July 13, 1787, until July 4, 1800), and then part of the Indiana Territory. On February 3, 1809, the 10th United States Congress passed legislation establishing the Illinois Territory, after Congress received petitions from residents in the Mississippi River areas complaining of the difficulties of participating in territorial affairs in Indiana Territory. The portions of the Illinois Territory north of what became the State of Illinois were in 1818 annexed to Michigan Territory, and after several administrative arrangements became a part of the Upper Peninsula of Michigan (1837), the State of Wisconsin (1848), and a northern section of the State of Minnesota (1858).
The Illinois Territory originally included lands that became the states of Illinois, Wisconsin, the eastern portion of Minnesota, and the western portion of the upper peninsula of Michigan. As Illinois was preparing to become a state, the remaining area of the territory was attached to the Michigan Territory.
The original boundaries of the Territory were defined as follows: "...all that part of the Indiana Territory which lies west of the Wabash river, and a direct line drawn from the said Wabash river and Post Vincennes, due north to the territorial line between the United States and Canada..."
End of the Territory
In 1818, the southern half of the territory was admitted to the United States as the State of Illinois. The northern half, modern Wisconsin and parts of modern Minnesota and Michigan became part of the Territory of Michigan.
- Historic regions of the United States
- History of Illinois
- Illinois Country
- Illinois Territory's At-large congressional district
- Illinois-Wabash Company
- List of governors of dependent territories in the 19th century
- List of governors of Illinois
- Military Tract of 1812
- Territorial evolution of the United States
- War of 1812
- Forstall, Richard L. (ed.). Population of the States and Counties of the United States: 1790–1990 (PDF) (Report). United States Census Bureau. p. 4. Retrieved May 18, 2020.
- Heidler, David Steohen and Heidler, Jeanne T., eds. "Illinois Territory," Encyclopedia of the War of 1812, (2004), Naval Institute Press, Online at Google Book Search, Accessed March 10, 2009, https://books.google.com/books?id=_c09EJgek50C
- Edwards, Ninian Wirt (1870). History of Illinois, from 1778 to 1833; and Life and Times of Ninian Edwards. pp. 28. Retrieved February 24, 2008.
- "Governor Ninian Edwards Biography". Genealogy Trails. Retrieved June 12, 2019.
- Act dividing Indiana Territory, 1809
- An Act to enable the people of the Illinois Territory to form a constitution and state government, and for the admission of such state into the Union on an equal footing with the original states (April 18, 1818)
- Resolution declaring the admission of the state of Illinois into the Union (December 3, 1818)
- Solon J. Buck: Illinois in 1818
- Animated Map: Boundaries of the United States and the Several States