Many UrbanismsNow, for the first time in history, the majority of the world's population lives in cities. But urbanization is accelerating in some places and slowing down in others. The sprawling megacities of Asia and Africa, as well as many other smaller and medium sized cities throughout the "Global South," are expected to continue growing. At the same time, older industrial cities in wealthier countries are experiencing protracted socioeconomic decline.