EarthPulse, Maps, Global Trends, Human Impact

Demographers predict that 2008 will be the dawn of the urban millennium, when, for the first time in human history, a majority of the world's people will live in cities and towns rather than in rural areas. And this urban growth is set to continue for decades. By 2030, Earth's population, now 6.6 billion, will grow by about 1.5 billion people, nearly all from cities.

Cities first arose on the plains of Mesopotamia more than 9,000 years ago, and humanity has been making a slow move away from the countryside ever since. But what was once a trickle has become a torrent, especially in Asia and Africa. In China alone, some 200 million people are transitioning from rural areas to the city.

Urban areas lure new residents with the prospect of a higher standard of living. But when populations outstrip a city's infrastructure and opportunities, life can become grim. A third of all city dwellers—more than one billion people—live in slums, without access to clean water, sanitation, and other necessities.

What the urban millennium will mean for humanity will depend largely on whether governments react adequately and in time to meet the demands of Earth's swelling cities.