Florida Keys, a chain of coral and limestone islands extending approximately 150 miles (240 km) southwest from the southeastern mainland of Florida and separating Florida Bay from the Straits of Florida. There are almost 1,000 islands in the Florida Keys. (The name keyis derived from the Spanish word cayo, meaning “small island,” or “islet.”) The easternmost island, Key Largo, is the largest—28 miles (45 km) long and up to 2 miles (3 km) wide. Key West is the chain's westernmost island. It is not the farthest west of the state's islands, however, since the Marquesas Keys and the Dry Tortugas also belong to Florida.
Vegetation and climate are tropical on all the Florida Keys. Fishing is the main occupation. The town of Key West is the only large settlement on the islands. The Overseas Highway, completed in 1938, extends from the Florida mainland to Key West, connecting the more important islands. A railroad connecting Key West with the mainland was destroyed by a hurricane in 1935. Before the United States acquired Florida from Spain in 1819, the Keys were a base of operations for pirates.