Earth's city lights in 2001
Earth's city lights in 2001 - 


Scott Jagow: A report coming out today predicts how many people will be on this planet by mid-century. Can you guess? Right now, we're at six and a half billion. Try 9.3 billion by 2050. More now from Jill Barshay.

Jill Barshay: City mouse is about to win out over country mouse.

Carl Haub is a demographer at the Population Reference Bureau. He predicts more than half of all people will live in urban areas starting in 2008.

Carl Haub: That's not all cities like Bombay and Shanghai. It's also the smaller cities, cities of say 500,000. That's really a major change. Many of those areas of developing countries have not had a city of really significant size and soon they will.

People are moving to cities to seek better lives. In some cases, there's not enough farmland for families to distribute to all their kids. Other times, people are lured away by higher paying factory jobs.

Haub says the list of the world's biggest cities will soon be changing.

Haub: Cities like say Dehli India will grow to be the world's largest city, even displacing Tokyo.

Haub says incomes generally rise with urbanization, as do slums.

I'm Jill Barshay for Marketplace.