Manhattan (/mænˈhætən/) is the smallest and most densely populated borough of New York City. Located primarily on the island of Manhattan at the mouth of the Hudson River, the borough is conterminous with New York County, an original county of the state of New York. The borough and county consist of Manhattan Island and several small adjacent islands: Roosevelt Island, Randall's Island, Wards Island, Governors Island, Liberty Island, part of Ellis Island, Mill Rock, and U Thant Island; as well as Marble Hill, a small area on the mainland bordering the Bronx. The original city of New York began at the southern end of Manhattan, expanded northward, and then between 1874 and 1898, annexed land from surrounding counties.
Located on one of the world's largest natural harbors, New York City consists of five boroughs, each of which is a county of New York State. The five boroughs—The Bronx, Brooklyn, Manhattan, Queens, and Staten Island—were consolidated into a single city in 1898. With a Census-estimated 2012 population of 8,336,697 distributed over a land area of just 302.64 square miles (783.8 km2), New York is the most densely populated major city in the United States. As many as 800 languages are spoken in New York, making it the most linguistically diverse city in the world. The New York City Metropolitan Area's population is the United States' largest, with 18.9 million people distributed over 6,720 square miles (17,400 km2), and is also part of the most populous combined statistical area in the United States, containing 22.1 million people as of the 2010 Census.