Cape Girardeau County is located in the southeastern part of the U.S. state of Missouri; its eastern border is formed by the Mississippi River. At the 2020 census, the population was 81,710. The county seat is Jackson, the first city in the US to be named in honor of President Andrew Jackson. Officially organized on October 1, 1812, the county is named after Ensign Sieur Jean Baptiste de Girardot, an official of the French colonial years.