Jackson is a city in and the county seat of Cape Girardeau County, Missouri, United States. It is a principal city of the Cape Girardeau–J…Jackson is a city in and the county seat of Cape Girardeau County, Missouri, United States. It is a principal city of the Cape Girardeau–Jackson, MO-IL Metropolitan Statistical Area. The population of Jackson was 15,481 at the 2020 census.