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 accessible 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
Great Flood of 1993
Great Flood of 1993
Kaskaskia, Illinois