The Florida Keys are a coral cay archipelago stretching southwest from near Miami to Key West and the Dry Tortugas, forming the southernmost part of the continental United States between the Atlantic Ocean and the Gulf of Mexico. First inhabited by the Calusa and Tequesta peoples and charted by Juan Ponce de León in 1513, the islands developed around wrecking, trade, and later transportation links. Their modern character reflects ancient reef and limestone formations reshaped by sea-level change, with the Florida Reef offshore. The Overseas Railway and later U.S. 1 made the Keys more accessible, while their close ties to Cuba and Caribbean ecology have helped shape a distinctive regional identity.