The Mississippi–Alabama barrier islands are a chain of barrier islands in the Gulf of Mexico along the coasts of Mississippi and Alabama enclosing the Mississippi Sound. The major islands are Cat Island, Ship Island, Horn Island, Petit Bois Island, and Dauphin Island; in the early 20th century the chain also included the Isle of Caprice, which has since been submerged. The islands are separated by wide inlets, several of which have been channelized to form the shipping channels for Gulf coast ports. The shapes and sizes of the islands have changed significantly since the 1800s, with the islands generally shrinking and shifting westward, especially after major tropical cyclones. Most of the islands are uninhabited. Much of the Mississippi portion of the chain is included in the Gulf Islands