The prolific Edward Glaeser writes,

28 percent of Manhattan’s payroll goes to workers in a single three-digit industry. 56 percent of Manhattan’s payroll goes to workers in four three-digit industries. New York’s 20th century success primarily reflects its ability to attract and retain a single industry, and its future appears related to a continuing ability to hold that industry.

The attraction of finance and business services to New York reflects the advantages of the city in facilitating face-to-face contact and the spread of information…the primary cost involved in the movement of people is the opportunity cost of time, which rises with wages. For this reason, cities, which represent the elimination of physical distance between people, still excel in delivering services. In addition, as the demand for timely information rises, the proximity which facilitates that flow of that information continues to be critical. The success of finance and business services on the island of Manhattan hinges critically on the advantage that the island has in bringing people together and speeding the flow of knowledge.