Kaskaskia is a village in Randolph County, Illinois, United States. In 2010 the population was only 14, making it the second-smallest incorporated community in Illinois. It was a major French colonial town of the Illinois Country. Its peak population was about 7,000 when it was a regional center. Kaskaskia became the capital of the Illinois Territory on February 3, 1809. In 1818, Illinois became the 21st U.S. state and Kaskaskia was its capital until 1819. 