Final answer:
Gulfport, Hattiesburg, and Biloxi are all cities located in the state of Mississippi, each known for their unique contributions to the state's economy and culture.
Step-by-step explanation:
The state that has Gulfport, Hattiesburg, and Biloxi is Mississippi. These cities are all significant in their own right within the state.
Gulfport is known for being a key economic and maritime hub, while Biloxi is famous for its casinos, tourism, and fishing industries. Hattiesburg, often called 'Hub City,' is an important center for education and the home to the University of Southern Mississippi.