Kaskaskia, Illinois
By 1950 only 112 people lived in Kaskaskia. By 1970 the population had fallen to 79, and it continued to fall to 33 in 1980.  The town was flooded with nine feet of water by the Great Flood of 1993, which reached the roofs of the buildings.  By 2000, with a only nine residents, Kaskaskia was almost a ghost town and the least populous incorporated community in the State of Illinois.