Manhattan is the most densely populated of the five boroughs of New York City. The borough is coterminous with New York County, founded on November 1, 1683 as an original county of the U.S. state of New York. The borough consists mostly of Manhattan Island, bounded by the East, Hudson, and Harlem Rivers, but also includes several small adjacent islands, as well as Marble Hill, a small neighborhood on the U.S. mainland.
Manhattan has been described as the economic and cultural center of the United States and serves as home to the United Nations Headquarters. Wall Street, in Lower Manhattan, has been called the financial capital of the world, and is home to the New York Stock Exchange and NASDAQ. Many multinational media conglomerates are based in the borough. Historically documented to have been purchased by Dutch colonists from Native Americans in 1626 for the equivalent of $24, Manhattan real estate has since become among the most expensive in the world, with the value of Manhattan Island itself estimated to exceed US$3 trillion in 2014.
New York County is the most densely populated county in the United States, and is more dense than any individual American city. It is one of the most densely populated areas in the world, with a Census-estimated 2013 population of 1,626,159 living in a land area of 22.96 square miles, or about 70,826 residents per square mile. On business days, the influx of commuters increases that number to over 3.9 million, or around 170,000 people per square mile. Manhattan has the third-largest population of New York’s five boroughs, after Brooklyn and Queens, and is the smallest borough in terms of land area.