Tallahatchie County is a county in the U.S. state of Mississippi. At the 2020 census, the population was 12,715. Its county seats are Charleston and Sumner. Tallahatchie County is located in the Mississippi Delta region, divided by the Tallahatchie River which runs from north to south through the county before joining what becomes the Yazoo River in LeFlore …Tallahatchie County is a county in the U.S. state of Mississippi. At the 2020 census, the population was 12,715. Its county seats are Charleston and Sumner. Tallahatchie County is located in the Mississippi Delta region, divided by the Tallahatchie River which runs from north to south through the county before joining what becomes the Yazoo River in LeFlore County.