New York City (officially the City of New York) is the most populous city in the United States of America. Its business, financial and trading organizations are significant players in the nation's economy and in the world. As a result, the city has the largest regional economy in the country. Home of the United Nations, the city is one of the world's diplomatic centers. The city is divided up into five boroughs (The Bronx, Brooklyn, Manhattan, Queens, and Staten Island) and has a population of 8.1 million within a land area of 321 square miles (830 km²). With a population of 18.7 million, the New York metropolitan area is one of the largest urban areas in the world.