Green Island is a coterminous town-village in Albany County, New York, United States some 8 miles (13 km.) north of Albany, New York. Green Island is one of only five such town-village amalgams in New York. The population was 2,620 at the 2010 census. The postal code is 12183.
Green Island is also the smallest town, by area, in New York, covering 0.7 of a square mile (1.8 km2); by contrast, the largest towns in the state by area are Brookhaven, which covers an area of 531.5 square miles (1,377 km2), though much of that is water, and Webb, which has the largest land area at 483 square miles (1,250 km2).
Today's town and village of Green Island is connected to the mainland. However, it was once called Tibbett's Island, and is situated on land that was, in the past, an island. The First (or South) Branch of the Mohawk River delta once ran between the island and Watervliet, separating the island from mainland Albany County. The river branch was filled in during construction of Interstate 787 in the 1960s.
Green Island was called by the Native Americans Pachanhanit or Nehanenesick, and was owned by the natives Amenhanit, Aepjen, and Wanapet until they sold it in 1665. The island was part of the Manor of Rensselaerswyck begun by the Patroon Kiliaen van Rensselaer, whose great-grandson (Colonel Kiliaen van Rensselaer) sold the island in 1708 to Colonel Pieter Schuyler.