How Population Lies; True, big cities no longer draw big numbers. But that doesn't mean their power is slipping too.(Cover story)

Byline: Saskia Sassen (Sassen's new book is "Territory, Authority, Rights: From Medieval to Global Assemblages.")

Why are New York, Paris and Seoul losing people? To some observers, particularly the champions of the small and the suburban, this suggests an increasing irrelevance. To me, that's missing the point.

Five years ago in "The Global City: New York, London, Tokyo," I argued that these metropolises had emerged in the mid-1980s as a dominant force by serving as the link between the national and the global economies. And as more countries open up to international markets, their leading business and financial centers are starting to function as global cities, too. In the late 1980s we saw the emergence of Sydney, Toronto, Singapore and Seoul, among others. The 1990s added Mumbai, Sao Paulo, Buenos Aires, Mexico City, Chicago and Shanghai. Cairo, Dubai, Manila, Jakarta and Kuala Lumpur have come on in the past five years. There are now about 40 such cities, up from a handful in the mid-'80s. Their growing power is evident in spiraling downtown real-estate prices and incomes.

The shrinking of big-city populations has been both oversold and misinterpreted. Population is growing in some global cities, like Shanghai, London and Chicago. And in global cities where population is falling or stagnating, from New York to Manila, there is an inflow of highly educated 20- to 35-year-olds, along with an outflow of the very young and the old. What's happening is a brutal triage: apartments that once held families now hold one single investment banker. And the space required by that single banker for offices, restaurants and shops can be two, three, four times more than that required by the family he or she replaces.

This is, in part, why the urban glamour zone is expanding in all these cities, often dramatically. Shanghai has built 5,000 high-rises in just the past seven years, New York has transformed Times Square from derelict to prime real estate, and despite more than a decade of warnings about its imminent demise, Hong Kong's property market still has so much momentum, it's continuing to eat up more of its famous harbor. In global cities, fewer people often means more intense economic activity. If anything, the elites who populate these glamour zones need more specialized services than ever, because the more countries one operates in, the more complex the challenges become. Indeed, one of the most powerful but overlooked ...