Roosevelt Island, formerly known as Welfare Island, and before that Blackwell's Island, is a narrow island in the East River of New York City. It lies between the island of Manhattan to its west and the borough of Queens to its east. Running from Manhattan's East 46th to East 85th streets, it is about two miles long, with a maximum width of 800 feet, and a total area of 147 acres. The island is part of the Borough of Manhattan and New York County. Together with Mill Rock Island, Roosevelt Island comprises New York County's Census Tract 238, which has a land area of .279 sq mi. [1] United States Census Bureau and had a population of 9,520 in 2000 according to the US Census. "An Island Joins the Mainstream" - New York Times (September 2, 2007) The Roosevelt Island Operating Corporation estimated its population was about 12,000 in 2007. According to the US Census 2000, Mill Rock Island (Census Block 9000) is unpopulated The land is owned by the city, but was leased to the State of New York's Urban Development Corporation for 99 years in 1969. Most of the residential buildings on Roosevelt Island are rental buildings. One (Rivercross) is a cooperative. One (Riverwalk Place) is a condo. One rental building (Eastwood) has left New York State's Mitchell-Lama affordable housing program, though current residents are protected. Three other buildings are now working toward privatization, including the cooperative.