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. state, the town briefly served as the state's first capital until 1819, when the capital was moved to Vandalia.
Most of the town was destroyed in April 1881 by flooding, as the Mississippi River shifted eastward to a new channel, taking over the lower of the Kaskaskia River. This resulted from deforestation of the river banks during the 19th century, due to crews taking wood for fuel to feed the steamboat and railroad traffic. The river now passes east rather than west of the town. The state boundary line, however, remained in its original location. Accordingly, if the Mississippi River is considered to be a break in physical continuity, Kaskaskia is an exclave of Illinois, lying west of the Mississippi and reachable only from Missouri. A small bridge crosses the old riverbed, now a creek that is sometimes filled with water during flood season. Kaskaskia has an Illinois telephone area code (618) and a Missouri ZIP Code (63673). Its roads are maintained by Illinois Dept. of Transportation, and its few residents vote in the Illinois elections. The town was evacuated in the Great Flood of 1993, which covered it with water more than nine feet deep (see photo below of church steeple amid rooftops).
In 2010, a program titled How the States Got Their Shapes on the History Channel featured Kaskaskia. The former Randolph County Sheriff was featured discussing different sites on Kaskaskia Island.