Port Gibson is a city and the county seat of Claiborne County, Mississippi, United States. The population was 1,567 at the 2010 census. It is bordered on the west by the Mississippi River. The first European settlers in Port Gibson were French colonists in 1729; it was part of their La Louisiane. After the United States acquired the territory from France in 1803 in the Louisiana Purchase, the town was chartered that same year.