We are at a global inflection point. Half the world's population is now urban -- and half the world's most global cities are Asian. The 2010 Global Cities Index, a collaboration between Foreign Policy, management consulting firm A.T. Kearney, and The Chicago Council on Global Affairs, reveals a snapshot of this pivotal moment. In 2010, five of the world's 10 most global cities are in Asia and the Pacific: Tokyo, Hong Kong, Singapore, Sydney, and Seoul. Three -- New York, Chicago, and Los Angeles -- are American cities. Only two, London and Paris, are European. And there's no question which way the momentum is headed: Just as more people will continue to migrate from farms to cities, more global clout will move from West to East.

And yet, even as we see the dramatic effects of globalization at work in the rise of up-and-coming cities like Bangalore, Sao Paulo, and Shanghai, what's also remarkable is just how dominant the great capitals of old-school commerce remain. New York, London, Tokyo, and Paris are the top four, as they were in the first Global Cities Index two years ago, and they are ahead in most of the criteria that make a truly global city. Influential networks boost global impact, and having a giant head start -- as New York does in market capitalization, Tokyo in Fortune Global 500 companies, and London in international travelers -- will only amplify those advantages in the future. Success breeds success.

So what makes a Global City? Not size alone, that's for sure; many of the world's largest megalopolises, such as Karachi (60), Lagos (59), and Kolkata (63), barely make the list. Instead, the index aims to measure how much sway a city has over what happens beyond its own borders -- its influence on and integration with global markets, culture, and innovation. To create this year's rankings, we analyzed 65 cities with more than 1 million people across every region of the globe, using definitive sources to tally everything from a city's business activity, human capital, and information exchange to its cultural experience and political engagement. Data ranged from how many Fortune Global 500 company headquarters were in a city to the size of its capital markets and the flow of goods through its airports and ports, as well as factors such as the number of embassies, think tanks, political organizations, and museums. Taken together, a city's performance on this slate of indicators tells us how worldly -- or provincial -- it really is.

The seats of traditional political power aren't necessarily the most global. Only four of the top 10 cities are national capitals. Washington comes in at No. 13. Beijing (15) edges out Berlin (16), which trounces Moscow (25). Two of the top 10 global cities are laws unto themselves, operating outside the jurisdiction of a separate national government (Hong Kong and Singapore). The sun set a half-century ago on the British Empire, and yet London continues to shine at No. 2. For now.

Photo: Robin Hammond / Panos