Long_Beach,_New_York Long Beach is a city in Nassau County, New York on a barrier island off the South Shore of Long Island and one of only two cities in the county. The other city is Glen Cove. As of the United States 2000 Census, the city population was 35,462. It was incorporated in 1923, and is nicknamed The City By the Sea (as seen, in Latin, on its official seal). The City of Long Beach is surrounded by the Town of Hempstead.