THE 21ST CENTURY WILL NOT BE dominated by America or China, Brazil or India, but by the city. In an age that appears increasingly unmanageable, cities rather than states are becoming the islands of governance on which the future world order will be built. This new world is not--and will not be--one global village, so much as a network of different ones.
Time, technology, and population growth have massively accelerated the advent of this new urbanized era. Already, more than half the world lives in cities, and the percentage is growing rapidly. But just 100 cities account for 30 percent of the world's economy, and almost all its innovation. Many are world capitals that have evolved and adapted through centuries of dominance: London, New York, Paris. New York City's economy alone is larger than 46 of sub-Saharan Africa's economies combined. Hong Kong receives more tourists annually than all of India. These cities are the engines of globalization, and their enduring vibrancy lies in money, knowledge, and stability. They are today's true Global Cities.
At the same time, a new category of megacities is emerging around the world, dwarfing anything that has come before. A massive influx of people has not only spurred the growth of existing cities, but created new ones virtually from scratch on a scale not previously imagined, from the factory towns in China's Guangdong province to the artificial "knowledge cities" rising in the Arabian desert. The defining feature of this new urban age will be megalopolises whose populations are measured in the tens of millions, with jagged skylines that stretch as far as the eye can see.
Many will pose challenges to the countries that give birth to them. For though no nation can succeed without at least one thriving urban anchor--and even then, a functioning Kabul or Sarajevo is still no guarantee of national survival--it's also true that globalization allows major cities to pull away from their home states, a reality captured by the massive and potentially dangerous wealth gap between city and countryside in second-world countries such as Brazil, China, India, and Turkey.
Neither 19th-century balance-of-power politics nor 20th-century power blocs are useful in understanding this new world. Instead, we have to look back nearly a thousand years, to the medieval age in which cities such as Cairo and Hangzhou were the centers of global gravity, expanding their influence confidently outward in a borderless world. When Marco Polo set forth from Venice along the emergent Silk Road, he extolled the virtues not of empires, but of the cities that made them great. He admired the vineyards of Kashgar and the material abundance of Xi'an, and even foretold--correctly--that no one would believe his account of Chengdu's merchant wealth. It's worth remembering that only in Europe were the Middle Ages dark they were the apogee of Arab, Muslim, and Chinese glory.
Now as then, cities are the real magnets of economies, the innovators of politics, and, increasingly, the drivers of diplomacy. Those that aren't capitals act like they are. Foreign policy seems to take place even among cities within the same country, whether it's New York and Washington feuding over financial regulation or Dubai and Abu Dhabi vying for leadership of the United Arab Emirates. This new world of cities won't obey the same rules as the old compact of nations; they will write their own opportunistic codes of conduct, animated by the need for efficiency, connectivity, and security above all else.
WESTERN CITIES HAVE dominated the ranks of leading urban centers since the Industrial Revolution, a testament to their educated workforces, strong legal systems, risk-taking entrepreneurs, and leading financial markets. New York and London together still represent 40 percent of global market capitalization. But look at the economic map today, and a major shift becomes apparent. …