Adams County is a county located in the U.S. state of Mississippi. As of the 2020 census, the population was 29,538. The county seat is Natchez. The county is the first to have been organized in the former Mississippi Territory. It is named for the second President of the United States, John Adams, who held that office when the county was organized in 1799. Adams County is part of the Natchez micropolitan area which consists of Adams County, Mississippi and Concordia Parish, Louisiana.