island in Upper New York Bay, formerly the United States' principal immigration reception centre. The island lies about 1 mile (1.6 km) southwest of Manhattan Island (Manhattan), New York City, and about 1,300 feet (400 metres) east of the New Jersey shore. It has an area of about 27 acres (11 hectares).

The island was named for Manhattan merchant Samuel Ellis, who owned it in the 1770s. For a time, ships' ballast was dumped there, and much of the island's current area consists of landfill. In 1808 the state of New York sold the island to the federal government, and it was used as a fort and powder magazine. It served as the nation's major immigration station from 1892 to 1924, after which its role was reduced; during that period an estimated 17 million immigrants passed through Ellis Island, where they were processed by immigration authorities and obtained permission to enter the United States. After immigration reception was moved to New York City proper in 1943, Ellis Island continued to serve as a detention station for aliens and deportees until 1954. It became part of Statue of Liberty National Monument (Liberty, Statue of) (along with nearby Liberty Island) in 1965 and was reopened to sightseers in 1976 by the National Park Service. The Main Building and other structures on the island were restored in the 1980s and opened in 1990 as the Ellis Island Immigration Museum.