OUR MIGRATION TO THE CITIES WORLD-WIDE IS SPEEDING UP. HOW WILL IT AFFECT US?

Our centuries-long steady migration of people into the cities passed a crucial milestone recently. More than half of humanity now lives in cities—and that figure will likely reach 75% by 2050. This urban shift is already visibly transforming newly sprawling giants such as Shanghai and Mexico City, as well as highly developed cities such as New York and London. This growth is also bringing titanic problems. The Endless City, a new book edited by the London School of Economics Ricky Burdett and design curator Deyan Sudjic, aims to put urban expansion into perspective. The growth of cities, they argue, is not just a problem for local government agents or urban planners. But urban growth is inseparable from major political and economic forces including globalization, immigration, employment, social exclusion, and sustainability (themes that track closely with the issues currently being debated in the runup to the U.S. Presidential election.).

The book is intended as a practical resource for those looking at rapid urban growth as an opportunity despite the approaching challenges and often stark inequalities. (1.4 billion people will be living in city slums by 2020). Berlin, its economy stagnant, is still reeling as the mass influx of citizens anticipated after the city's reunification nearly 20 years ago failed to materialize. In contrast, Mexico City's uncontrolled expansion over the past 20 years sees 60% of its nearly 20 million inhabitants living in illegal and informal housing, creating vast, unplanned, and sometimes dangerous communities. And just as New York is managing its post-September 11 growth, Johannesburg is searching for a cohesive identity as it has been transformed from an all-white city of about 250,000 in 1994 to a post-apartheid, multi-ethnic conglomeration of some 3.25 million inhabitants today.

The chapter "Interventions," meanwhile, is a curated set of 20 innovative projects that give practical responses to many of the challenges introduced earlier in the book. Particularly compelling examples include New York's Hearst Tower, a successful environmentally conscious building; and Mexico City's Metrobus project, a bold attempt to implement a system of public buses catering to the entire metropolis to begin easing the city's infamous traffic congestion. Finally the chapter on "Positions," puts forward an agenda of smarter urban planning. Managing the coming surge in urban populations, they argue, will require the worldwide collaboration of designers, architects, and politicians. That this is the book's thinnest section suggests the majority of the endless city's story has yet to be told.