Harrison County, Mississippi in the context of Hurricane Camille

Gulfport (/ˈɡʌlfˌpɔːrt/ GUHLF-port) is a port city in Harrison County, Mississippi, United States, and its co-county seat. It had a population of 72,926 at the 2020 census, making it the second-most populous city in Mississippi after Jackson. The Gulfport–Biloxi metropolitan area had a population of 416,259. Gulfport lies along the Gulf Coast of the United States in southern Mississippi, taking its name from its port on the Gulf Coast on the Mississippi Sound.

Gulfport emerged from two earlier settlements, Mississippi City and Handsboro. Founded in 1887 by William H. Hardy as a terminus for the Gulf and Ship Island Railroad, the city was further developed by Philadelphia oil tycoon Joseph T. Jones, who funded the railroad, harbor, and channel dredging. The city was officially incorporated in 1898. By the early 20th century, Gulfport had become the largest lumber export city in the United States, though this faded with the depletion of Mississippi's Piney Woods. The city transitioned into tourism through its white beaches, grand hotels, and significant casino gaming operations.

Biloxi (/bɪˈlʌksi/ bih-LUK-see; French: [bilusi]) is a city in Harrison County, Mississippi, United States. It lies on the Gulf Coast in southern Mississippi, bordering the city of Gulfport to its west. The adjacent cities are both designated as seats of Harrison County. The population of Biloxi was 49,449 at the 2020 census, making it the state's fourth-most populous city. It is a principal city of the Gulfport–Biloxi metropolitan area, home to 416,259 residents in 2020. The area's first European settlers were French colonists.

The beachfront of Biloxi lies directly on the Mississippi Sound, with barrier islands scattered off the coast and into the Gulf of Mexico. Keesler Air Force Base lies within the city and is home to the 81st Training Wing and the 403rd Wing of the U.S. Air Force Reserve.

Long Beach is a city located in Harrison County, Mississippi, United States. It is part of the Gulfport-Biloxi metropolitan area. As of the 2020 census, the city had a population of 15,829.

The Gulfport–Biloxi Metropolitan Statistical Area is a metropolitan statistical area (MSA) in the Mississippi Gulf Coast region that includes four counties – Hancock, Harrison, Jackson and Stone. The principal cities are Gulfport and Biloxi. The 2010 census placed the Gulfport-Biloxi MSA population at 388,488, though as of 2019, it was estimated to have increased to 417,665. The area was significantly impacted by Hurricane Katrina on August 29, 2005, and prior to the hurricane, had experienced steady to moderate population growth. However, growth has since rebounded, with the population steadily increasing every year throughout the 2010s.

Mississippi City is an unincorporated community in Harrison County, Mississippi, United States. It is part of the Gulfport–Biloxi, Mississippi Metropolitan Statistical Area. The community was annexed by Gulfport, Mississippi in 1965.

In 1870, the Louisville and Nashville Railroad was constructed through the southernmost section of Harrison County, Mississippi, connecting New Orleans, Louisiana, and Mobile, Alabama. A northern transportation route into south Mississippi was provided by the Gulf and Ship Island Railroad at the turn of the 20th century. These railroads provided an inexpensive means for moving passengers as well as goods, and opened south Mississippi to both industrial and recreational development.Rapidly progressing lumber and seafood industries transformed the Mississippi Gulf Coast in the 1920s, and people arrived from throughout the United States to take advantage of the economic boom. Northern tourists were attracted to the Mississippi Gulf Coast because of mild winters and cool sea breezes in summer, before the introduction of air conditioning. Besides the weather, other tourist attractions included seafood restaurants, swimming, golf, schooner races, sailing to offshore islands, and recreational fishing. During this period of economic expansion, grand hotels were constructed along the Mississippi Gulf Coast to accommodate businessmen, tourists, and transient workers. Most of these grand hotels no longer exist; and of the two structures that were still standing after the first decade of the 21st century, neither served as a lodging establishment. Together, these grand hotels represented an important era in the history of the Mississippi Gulf Coast throughout the 20th century.

Keesler Air Force Base (IATA: BIX, ICAO: KBIX, FAA LID: BIX) is a United States Air Force base located in Biloxi, a city along the Gulf Coast in Harrison County, Mississippi, United States. The base is named in honor of aviator 2d Lt Samuel Reeves Keesler Jr., a Mississippi native killed in France during the First World War. The base is home of Headquarters, Second Air Force (2 AF) and the 81st Training Wing (81 TW) of the Air Education and Training Command (AETC).

The base has specialized in ground trade training since its opening in 1941 during World War II. It has had high-quality technical schools and absorbed units moved from other bases under the Base Realignment and Closure Act (BRAC).