Yet this urban prosperity machine can be brutal. More than 1 billion people live in slums and squatter communities worldwide.
Jobs can be difficult to come by, especially in the fast-growing cities in Africa and Latin America.
Pollution from cars, factories and sewage threatens public health. The U.N. State of the World's Cities report, released Monday, comes five years into an initiative aimed at addressing those problems. At a 1996 meeting in Istanbul, Turkey, more than 170 nations agreed to the common goals of building sustainable settlements and providing adequate shelter for all. At a second meeting in New York this week, dubbed Habitat II, the parties to that agreement will gather to assess their progress and offer solutions. Much of the meeting will be devoted to sharing experiences and advice.