Manhattan 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. New York County is the most densely populated county in the United States, and one of the most densely populated areas in the world, with a 2010 population of 1,585,873 living in a land area of 22.96 square miles, or 69,464 residents per square mile (26,924/km²), more dense than any individual American city. It is also one of the wealthiest counties in the United States, with a 2005 per capita income above $100,000. Manhattan is the third-largest of New York's five boroughs in population, and its smallest borough in land area. Manhattan is the economic and cultural center of the United States. Anchored by Wall Street in Lower Manhattan, New York City functions as the financial capital of the world, with an estimated GDP of over $1.2 trillion, and is home of both the New York Stock Exchange and NASDAQ. Many multinational media conglomerates are based in the borough. Manhattan has many famous landmarks, tourist attractions, museums, and universities. It is also the location of the United Nations Headquarters. It is the cultural and economic center of New York City and the New York metropolitan area, hosting the seat of city government and a large portion of the area's employment, business, and entertainment activities. As a result, residents of New York City's other boroughs such as Brooklyn and Queens often refer to a trip to Manhattan as "going to the city", despite the comparable populations between those boroughs, and the fact that these boroughs are also part of the city proper. New York's five boroughs overview Jurisdiction Population Land area Borough of County of 1 July 2011 Estimates square miles squarekm Manhattan New York 1,619,090 23 59 The Bronx Bronx 1,408,473 42 109 Brooklyn Kings 2,565,635 71 183 Queens Queens 2,272,771 109 283 Staten Island Richmond 470,728 58 151 City of New York 8,336,697 303 786 State of New York 19,570,261 47,214 122,284 Source: United States Census Bureau