By 2030, an estimated 2 billion of the 5 billion people who will be living in cities will live in slums, primarily in Africa and Asia.
"Already these slums are huge. According to Mike Davis, author of Planet of Slums, nearly 80% of Nigeria's urban population, or some 41.6 million people, live in slums."
..."To the outsider, many developing-world slums look unbearably awful, but to their residents they do function, complete with social hierarchies, commerce and a degree of home-grown government. Still, when one sees a family living in a flyblown concrete cell in Karachi, inside a mud hut in Nairobi or in a cardboard shack in Lagos, one might be inclined to ask, Are they really better off than in the villages they fled? Dismal though the slums may be, the answer is often yes."
..."Mega-cities, of 10 million or more, are on the rise across Asia, while cities like Dhaka, Jakarta, Lagos and Delhi will cross the 20 million threshold by 2020. Planning and building is not keeping pace."
[Editor's note: This is one article in a Forbes series on "Twenty-First Century Cities". Links to the other stories appear below.]