Long Island, New York, an island extending eastward from the southeastern corner of the state. It is bounded on the north by Long Island Sound, on the east and south by the Atlantic Ocean, and on the west by New York Bay, the Narrows, and the East River. (For map, Its area is 1,401 square miles (3,630 km2). The island has a maximum length (east-west) of 118 miles (190 km) and a maximum width of 23 miles (37 km). Its surface consists of a plain that is somewhat higher in the north than in the south. Two low ridges run through the island, forming narrow peninsulas at the eastern end.

Long Island is divided into four counties: Kings (Brooklyn), Queens, Nassau, and Suffolk. Kings and Queens counties, on the western end, are boroughs of New York City. Although they form less than 13 per cent of Long Island's area, they contain more than 60 per cent of the population. Nassau County is composed mainly of residential suburbs of New York City. Suffolk County also has suburbs but is more rural, containing many fish hatcheries and vegetable and poultry farms. Heavy industry is concentrated mainly in Kings and Queens counties.

During the summer New Yorkers flock to Long Island's southern shore, which includes fine beaches such as the Rockaways, Jones Beach, Long Beach, and Fire Island. The fashionable northern shore has numerous bays and inlets. Many wealthy New Yorkers have summer estates here. Sagamore Hill, the home of President Theodore Roosevelt, is near Oyster Bay and is open to the public. Walt Whitman's birthplace is preserved as a historical site at nearby Huntington.

Major educational institutions on Long Island include the U.S. Merchant Marine Academy at Kings Point, Adelphi University at Garden City, Hofstra University at Hempstead, and a campus of the State University of New York (SUNY) at Stony Brook. Brookhaven National Laboratory for nuclear research is in Upton.

Long Island was discovered in 1609 by Henry Hudson. Dutch settlements were established on the western end of the island, and Englishmen settled to the east. In 1664 the entire island passed to English control. During the Revolutionary War, Long Island was occupied by the British after the patriots lost the Battle of Long Island in 1776. The population in 2000, including Kings and Queens counties, was 7,448,618.