Kaskaskia is a historically important village in Randolph County, Illinois, United States. In the 2010 census the population was 14, making it the second-smallest incorporated community in the State of Illinois in terms of population, behind Valley City (pop. 13). As a major French colonial town of the Illinois Country, in the 18th century its peak population was about 7,000, when it was a regional center. During the American Revolution, the town, which by then had become an administrative center for the British Province of Quebec, was taken by the Virginia militia during the Illinois campaign. It was designated as the county seat of Illinois County, Virginia, after which, it became part of the Northwest Territory in 1787. Kaskaskia was later named as the capital of the United States' Illinois Territory, created on February 3, 1809. In 1818, when Illinois became the 21st U.S.