Long Island is an island in the U.S. state of New York. Stretching northeast from New York Harbor into the Atlantic Ocean, the island comprises four counties, including two (Kings and Queens) that form the New York City boroughs of Brooklyn and Queens, and two (Nassau and Suffolk) that are farther out on the island and mainly suburban. Although all four counties are part of the greater New York metropolitan area, the name "Long Island" is often reserved in popular usage for only Nassau and Suffolk counties, as distinct from those lying within New York City proper. North of the island is Long Island Sound, across which are the states of Connecticut and Rhode Island.
With a Census-estimated population of 7,740,208 in 2013, embodying nearly 40% of New York State's population, Long Island is the most populated island in any U.S. state or territory, and the 17th-most populous island in the world (ahead of Ireland, Jamaica, and Hokkaidō). Its population density is 5,402 inhabitants per square mile (2,086 /km2). If it were a U.S. state, Long Island would rank 13th in population (after Virginia) and first in population density.
Both the longest and the largest island in the contiguous United States, Long Island extends 118 miles (190 km) eastward from New York Harbor to Montauk Point, with a maximum north-to-south distance of 23 miles (37 km) between Long Island Sound and the Atlantic coast. With a land area of 1,401 square miles (3,629 km2), Long Island is the 11th-largest island in the United States and the 148th-largest island in the world — larger than the 1,214 square miles (3,140 km2) of the smallest state, Rhode Island.
Two of New York City's major airports, LaGuardia Airport and JFK International Airport, are located on Long Island, in Queens. Nine bridges and 13 tunnels (including railroad tunnels) connect Brooklyn and Queens (and thus Long Island) to the three other boroughs of New York City. Ferries connect Suffolk County northward across Long Island Sound to the state of Connecticut.