Glen Cove is a city in Nassau County, on the North Shore of Long Island, New York, United States. The city's population was 28,365 at the tim…Glen Cove is a city in Nassau County, on the North Shore of Long Island, New York, United States. The city's population was 28,365 at the time of the 2020 census. Of Nassau County's five municipalities, Glen Cove is one of two that are cities, rather than towns – the other being Long Beach.