Since the ancient Greeks, cities have been engines of progress, creativity, and prosperity. Every month, five million people move into the cities of the world, and today more than half of humanity is urban. Despite improvements in communication that bring the entire world closer together, dense physical proximity is more important than ever to the productivity of urban centers.

New York typifies the history and future of cities. Since its founding, the famous metropolis has been an important commercial hub; by the late 19th century, it was the largest port and most populous city in the US. During the 20th century, globalization reduced New York’s shipping advantage but increased its edge in idea production, especially in design and finance. “Today, 40 percent of Manhattan’s payroll is in the financial services industry” (5), and Manhattan’s average salary is 170% higher than the US average.

Big US cities have big advantages, their workers earning 30% more and producing 50% more than those in outlying areas. Cities in the developing world, many of which suffer problems that once plagued the likes of San Francisco and Singapore, lately are breaking through to the production of ideas. Bangalore in India, for example, boasts a concentration of talented workers that can quickly develop commercial concepts and share them efficiently with other urban centers around the globe.