Cape Girardeau County was organized on October 1, 1812, as one of five original counties in the Missouri
 Territory after the US made the Louisiana Purchase of 1803. It is named after Ensign Sieur Jean Baptiste
 de Girardot (also spelled Girardeau or Girardat), a French officer stationed 1704–1720 at Kaskaskia in the
 Illinois Country of New France. In 1733 he founded a trading post on the Mississippi River, which
 developed as the present-day city of Cape Girardeau.[3] The "cape" in the county name was a rock
 promontory overlooking the Mississippi River and Claire's house; the original cape rock was destroyed by
 railroad construction.

 Jackson, Missouri is the county seat. The first Cape Girardeau County Courthouse was constructed in
 1818 by John Davis. This courthouse burned in 1870. The present courthouse in Jackson was completed in
 1908 and was designed by P.H. Weathers.