Ellis Island, island, c.27 acres (10.9 hectares), in Upper New York Bay, SW of Manhattan island. Government-controlled since 1808, it was long the site of an arsenal and a fort, but most famously served (1892–1954) as the chief immigration station of the United States. It is estimated that 40% of all Americans had an ancestor arrive at Ellis Island. Now part of the Statue of Liberty National Monument (see Liberty, Statue of), the island was opened to tourists in 1976. In 1990 an immigration museum was opened, and many records of immigrant arrivals have been computerized and are available there and on line. In 1998 the U.S. Supreme Court ruled that, pursuant to an 1834 interstate compact, only the original 3.3 acres (1.3 hectares) belong to New York, the remainder (created by landfill operations) belongs to New Jersey. See also Angel Island.