Cape Girardeau County is a county located in the southeastern part of the U.S. state of Missouri; its eastern border is formed by the Mississippi River. As of the 2010 U.S. Census, the population was 75,674. 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 Giradot, an official of the French colonial years.