World Meets Population Threshold: Most Now Live In Cities

The world quietly reached an historic milestone this week, when the population balance tipped from rural to urban. Throughout human history, a majority lived in rural areas, where farming and subsistence living dominate. Now, cities -- many of them teeming megacities marked by shantytown squalor -- dominate, if only by a hair. Demographers expected the weight to fall on cities, and the day -- May 23, 2007 -- was little heralded. But it marks a stunning transformation in modernization and demonstrates clearly why the recent focus of the world's mayors has been on sustainablity and climate change. For more on the switch to urban living, click here.