city, Miami-Dade county, southeastern Florida, U.S. It lies on a barrier island between Biscayne Bay (west) and the Atlantic Ocean (east), just east of Miami. The area was originally inhabited by Tequesta and later by Seminole Indians. Until 1912 the site was a mangrove swamp, where growers tried unsuccessfully to establish coconut plantations but had better luck with avocado groves. John S. Collins, Carl Fisher, and John and James Lummus pioneered real estate development (urban planning) there, and through their efforts a bridge was built across the bay (followed by a causeway in 1920). Dredging subsequently added land area to the island. The city was incorporated in 1915 as Ocean Beach, and the name was changed to Miami Beach the following year.