At the start of the 20th century, 10 percent of the earth’s population lived in cities. By the end of this decade, 50 percent will be urban dwellers. By 2015, there will be 58 metro areas with more than 5 million inhabitants each. Of these enclaves, 48 will be located outside the developed world. The lower-profile cities – those like Bombay, Lagos, and Dhaka – are flourishing the most, while traditional mega-metropolises, such as London, Osaka, and Detroit, are stagnating.
The world’s population booms and busts every 60 minutes. Here’s a look at the net population change per hour – from migrations, births, and deaths – for the fastest-growing and fastest-declining cities.