Key Biscayne is an island town in Miami-Dade County, Florida, United States. The population was 14,809 at the 2020 census, up from 12,344 in 2010. Geography Key Biscayne lies south of Miami Beach and east of Miami. The village is connected to Miami via the Rickenbacker Causeway, originally built in 1947. Because of its low elevation and direct exposure to the Atlantic Ocean, it is usually among the first Miami areas to be evacuated before an oncoming hurricane. According to the U.S. Census Bureau, the town has a total area of . of it are land and of it (27.0%) are water. The village is bordered on the north by Crandon Park, a Miami-Dade County park; on the south by Bill Baggs Cape Florida State Park; on the east by the Atlantic Ocean; and on the west by Biscayne Bay. History While there had been earlier schemes to develop a town on Key Biscayne, it wasn't until the opening of the Rickenbacker Causeway from Miami to Virginia Key and on to Key Biscayne in 1947 that the island was opened up to large-scale residential development. The northern two-thirds of the island had been operated as the largest coconut plantation in the continental United States during the first half of the 20th century. In 1940 the Matheson family donated over of their land to Dade County for a public park (Crandon Park) in exchange for a commitment that the county would build a causeway to the island. The remaining Matheson property, stretching across the middle of the island, was then sold off to developers. Starting in 1951, the Mackle Construction Company offered new homes on the island for US$9,540, with just US$500 down. A U.S. Post Office contract branch was opened, the Community Church started holding services in an old coconut-husking shed, and the Key Biscayne Elementary School opened in 1952. The southern third of Key Biscayne, which included Cape Florida, was owned by James Deering and, after his death, by his brother Charles, for 35 years. In 1948 José Manuel Áleman, a Cuban politician in exile, bought the Cape Florida property from the Deering estate. After Áleman died in 1951, his widow, Elena Santeiro Garcia, added to her Cape Florida property by buying an ocean-to-bay strip that had been part of the Matheson property. This strip included a canal that had been dug by William Matheson in the 1920s, and