Port Gibson is a city in Claiborne County, Mississippi, United States. The population was 1,567 at the 2010 census. Port Gibson is the county seat of Claiborne County and home to the Claiborne County Courthouse.The first European settlers in Port Gibson were French colonists in 1729; it was part of La Louisiane. It was chartered as a town in the U.S. in 1803 after the Louisiana Purchase. Due to development of cotton plantations in the area after Indian Removal, planters in the state imported thousands of African-American slaves from the Upper South. The county had a black majority established well before the Civil War; they were overwhelmingly enslaved.Several notable people are natives of Port Gibson. The town saw action during the American Civil War. Port Gibson has several historical sites listed on the National Register of Historic Places.