Editors' foreword.

• Position: Editorial

In its sixty-five-year history, the Journal of International Affairs has explored some of the most important transformations of the postwar world: from the U.S. occupation of Germany and Japan to the collapse of the Soviet Union, from democratization and development to the explosion of global trade. The unprecedented--and accelerating--growth of cities today will prove to be no less important. Mass urbanization will have a transformative effect on the political, economic and social fabrics of societies around the world. The demographic shift from rural to urban areas promises to release untapped human potential--creative and productive energies that will emerge from the increased exchange of ideas and capital.

However, managing this transition will be difficult. The diverse backgrounds of our authors and contributors--who hail from academia, think tanks and the public and private sectors--highlight the range of issues that arise during periods of rapid change. Urban planners and city governments will face complex new challenges requiring just the right mix of solutions. Urban problems will become, almost by definition, national and international problems. In broad terms, our authors and contributors examine "The Future of the City" through political, economic, social-equity and environmental lenses, and propose solutions that make it more likely that this new urban project will be a success.

The issue opens with an article from Andres Cadena, Richard Dobbs and Jaana Remes, experts from McKinsey & Company and the McKinsey Global Institute. They explore how cities in emerging markets will gain significant economic power over the next decade and a half, and how midsized cities--not just megacities--will soon play an outsized role in the global economy.

The next four articles discuss the sustainability of urban policies and address, respectively, the environment, religion and civic rights, political consent and housing. Xuefei Ren examines urban environmental policy in the world's most populous nation--China--and finds that green initiatives are often self-conscious ventures introduced to aggrandize cities and the officials who lead them. In light of the Arab Spring, Nezar AlSayyad and Mejgan Massoumi discuss the conflict between urbanization in the Arab world and the increasing influence of religion in the cities of democratizing nations.

Ester R. Fuchs uses her experience working in New York City government to argue that the political...