Part of the early 20th century Gold Coast of the North Shore, Glen Cove has a diverse population. Glen Cove is one of the two of Nassau County's five municipalities that is a city, rather than a town. The other city in Nassau County is Long Beach on the South Shore.
Succeeding cultures of indigenous peoples had lived in the area for thousands of years. At the time of European contact, the Lenape (Delaware) nation inhabited western Long Island, the areas of New York and New Jersey around the harbor and along the coast through present-day Pennsylvania and Delaware, as well as along the Delaware River. They spoke an Algonquian language. By 1600 the band inhabiting the local area was called the Matinecock after their location, but they were Lenape people, as were all the Native Americans living on western Long Island.
Glen Cove was used as a port by English migrants from New England and named "Moscheto" before 1668. On May 24, 1668 Joseph Carpenter of Warwick, Rhode Island purchased about of land to the northwest of the Town of Oyster Bay from the Matinecock. Later in that year he admitted four co-partners into the project: three Coles brothers, Nathaniel, Daniel, and Robert; and Nicholas Simkins, all residents of Oyster Bay. The five young men named the settlement Musketa Cove. In the Lenape language musketa meant “place of rushes.” The five men are considered the five original proprietors of Musketa Cove Plantation.
In the 1830s, steamboats started regular service on Long Island Sound between New York City and Musketa Cove, arriving at a point still called "The Landing." As "Musketa" was negatively associated with mosquito, in 1834 village residents changed the name to Glen Cove (said to be the misheard suggestion "Glencoe", after the Scottish glen) now Glencoe, Scotland. The village added population as workers arrived for jobs at the Duryea Corn Starch factory, which operated until 1900. The name "Duryea" was once suggested as a village name to replace Mosquito Cove but rejected.
By 1850 the village of Glen Cove had become a popular summer resort community for New York City residents. The Long Island Railroad was extended to Glen Cove in 1867, providing quicker, more frequent service to New York City. The availability of the train and the town's location on Long Island Sound made it attractive to year-round residents, and the population increased. On June 8, 1917, Glen Cove became an independent city, separating from the Town of Oyster Bay after 250 years.
The vistas afforded of Long Island Sound from the town's rolling hills attracted late 19th-century wealthy industrial barons, including Charles Pratt and his sons, J. P. Morgan, and F. W. Woolworth. They built large private estates along the island's North Shore. This expanse of settled wealth was part of what would become known in the 1920s as the Gold Coast. Part of the Morgan property was donated to the city and is now Morgan Park and Beach.
Most of the mansions were adapted to other purposes before the mid-20th century. Winfield Hall, the former home of F.W. Woolworth, is privately owned. Altogether, five Pratt families owned about 5,000 acres in the area. John T. Pratt's estate ("The Manor," designed by Charles A. Platt) is now operated as the Glen Cove Mansion Hotel and Conference Center. The Braes, the country estate of his son Herbert L. Pratt, was purchased by the Webb Institute in 1945. After renovation, it opened the facility in 1947 as an established specialty college for naval architecture and engineering. George DuPont Pratt's estate, Killenworth, was purchased by the Soviet Union government for use by its United Nations delegation. The Russians have used it for decades to house visitors and as a weekend retreat for its UN staff. When in the United States for meetings at the United Nations, both Nikita Khrushchev, then premier of the Soviet Union, and Fidel Castro, then president of Cuba, separately stayed at Killenworth.
Like many other suburbs, Glen Cove grew rapidly in population after World War II, when new residential developments were completed that replaced pastureland and farms with subdivisions. Many residents were second and third-generation descendants of eastern and southern European immigrants, and had moved out from childhood homes in Queens or Brooklyn. In the late 20th century, immigrants have come generally from Latin America and eastern Asia. A Sikh gurdwara established in Glen Cove draws from the ethnic East Asian population in the area.
The U.S. Post Office at Glen Cove was listed on the National Register of Historic Places in 1989, and the Justice Court Building, the former city court and later city hall and police headquarters, was added in 1990. It has been acquired for renovation as the North Shore Historical Museum.