New York County, which has the same boundaries as the Borough of Manhattan (and which should not be confused with New York City), is the most densely populated county in the United States, with a 2008 population of 1,634,795 living in a land area of 22.9 square miles (59.47 km²), or 71,201 residents per square mile (27,485/km²). It is also one of the wealthiest counties in the United States, with a 2005 personal income per capita above $100,000.Manhattan is one of the five boroughs of New York City, located primarily on Manhattan Island at the mouth of the Hudson River.  Manhattan is the third-largest of New York's five boroughs in population but the smallest in area.

The skyscraper, which has shaped Manhattan's distinctive skyline, has been closely associated with New York City's identity since the end of the 19th century. From 1890–1973, the world's tallest building was in Manhattan, with nine different buildings holding the title.The New York World Building on Park Row, was the first to take the title, standing 309 feet (91 m) until 1955, when it was demolished to construct a new ramp to the Brooklyn Bridge.] The nearby Park Row Building, with its 29 stories standing 391 feet (119 m) high took the title in 1899. The 41-story Singer Building, constructed in 1908 as the headquarters of the eponymous sewing machine manufacturer, stood 612 feet (187m) high until 1967, when it became the tallest building ever demolished.The Metropolitan Life Insurance Company Tower, standing 700 feet (213 m) at the foot of Madison Avenue, wrested the title in 1909, with a tower reminiscent of St Mark's Campanile in Venice. The Woolworth Building, and its distinctive Gothic architecture, took the title in 1913, topping off at 792 feet (241 m).
Manhattan is a major commercial, financial, and cultural center of both the United States and the world. Most major radio, television, and telecommunications companies in the United States are based here, as well as many news, magazine, book, and other media publishers. Manhattan has many famous landmarks, tourist attractions, museums, and universities. It is also home to the headquarters of the United Nations. Manhattan shopping is a major attraction to tourists visiting the island, in addition to viewing performances of opera, ballet, and, of course, Broadway productions.

Manhattan is the economic engine of New York City, with its 2.3 million workers drawn from the entire New York metropolitan area accounting for almost two-thirds of all jobs in New York City. Manhattan's daytime population swells to 2.874 million, with commuters adding a net 1.337 million people to the population. This commuter influx of 1.459 million workers coming into Manhattan was the largest of any other county or city in the country, and was more than triple the 481,000 commuters who headed into second-ranked Washington, D.C.
Its most important economic sector is the finance industry, whose 280,000 workers earned more than half of all the wages paid in the borough. The securities industry, best-known by its center in Wall Street, forms the largest segment of the city's financial sector, accounting for over 50% of the financial services employment. Before the financial crisis of 2008, the five largest securities-trading firms in the U.S. had their headquarters in Manhattan.In 2006, those in the Manhattan financial industry earned an average weekly pay about $8,300 (including bonuses), while the average weekly pay was about $2,500. The health care sector represented 11.3% of the borough's jobs and 4% of total compensation, with workers taking home about $900 per week.