Claiborne County is a county located in the U.S. state of Mississippi. As of the 2020 census, the population was 9,135. Its county seat is Port Gibson. The county is named after William Claiborne, the second governor of the Mississippi Territory. Claiborne County is included in the Vicksburg, MS Micropolitan Statistical Area as well as the Jackson-Vicksburg-Brookhaven, MS Combined Statistical Area. It is bordered by the Mississippi River on the west and the Big Black River on the north.