Miami Beach is a coastal resort city in Miami-Dade County, Florida. It was incorporated on March 26, 1915. The municipality is located on natural and man-made barrier islands between the Atlantic Ocean and Biscayne Bay, the latter of which separates the Beach from the mainland city of Miami. The neighborhood of South Beach, comprising the southernmost 2.5 sq mi (6.5 km2) of Miami Beach, along with Downtown Miami and the PortMiami, collectively form the commercial center of South Florida. Miami Beach's population is 82,890 according to the 2020 census. Miami Beach is the 26th largest city in Florida based on official 2019 estimates from the U.S. Census Bureau. It has been one of America's pre-eminent beach resorts since the early 20th century.