Illinois County, Virginia
Illinois County, Virginia, was a political and geographic region, part of the British Province of Quebec, claimed during the American Revolutionary War on July 4, 1778 by George Rogers Clark of the Virginia Militia, during the Illinois Campaign. It was formally recognized by the Commonwealth of Virginia later that year. The County was accorded official governmental existence, including legally defined boundaries and a formal governmental structure under the laws of the Commonwealth. The county seat was Kaskaskia. Its existence also has a defined end-point in 1784, when the Commonwealth of Virginia ceded the land to the United States federal government. The area later became part of the Northwest Territory by an Act of Congress in 1787. The county was bordered to the southeast by the Ohio River at the time of its existence. It is not within the boundaries of the modern-day state of Virginia.
See also 
- James, James Alton. The Life of George Rogers Clark. Chicago: University of Chicago Press, 1928. ISBN 1-4286-1023-5. p,157