THERE IS SOMETHING VISCERALLY REPULSIVE about urban poverty: the stench of open sewers, the choking smoke of smoldering trash heaps, the pools of fetid drinking water filmed with the rainbow color of chemical spills. It makes poverty in the countryside seem almost Arcadian by comparison. The rural poor may lack nutrition, health care, education, and infrastructure; still, they do the backbreaking work of tending farms in settings that not only are more bucolic, but also represent the condition of most of humanity for most of history. With life so squalid in urban slums, why would anyone want to move there?
Because slums are better than the alternative. Most people who've experienced both rural and urban poverty choose to stay in slums rather than move back to the countryside. That includes hundreds of millions of people in the developing world over the past few decades--and 130 million migrant workers in China alone. They follow a well-trodden path of seeking a better life in the bright lights of the city--think of Dick Whittington, the 14th-century rural migrant who ended up lord mayor of London. The good news is that the odds of living that better life are better than ever. For all the real horrors of slum existence today, it still usually beats staying in a village.
Start with the simple reason that most people leave the countryside: money. Moving to cities makes economic sense--rich countries are urbanized countries, and rich people are predominantly town and city dwellers. Just 600 cities worldwide account for 60 percent of global economic output, according to the McKinsey Global Institute. Slum dwellers may be at the bottom of the urban heap, but most are better off than their rural counterparts. Although about half the world's population is urban, only a quarter of those living on less than a dollar a day live in urban areas. In Brazil, for example, where the word "poor" conjures images of both Rio's vertiginous favelas and indigenous Amazonian tribes living in rural privation, only 5 percent of the urban population is classified as extremely poor, compared with 25 percent of those living in rural areas.
But is it much of a life, eking out an existence in today's urban squalor? Our image of modern slums comes from films like Slumdog Millionaire and books like Katherine Boo's Behind the Beautiful Forevers, portraits of India's urban underclass not all that far removed from the horrifying picture of 19th-century industrialization in Charles Dickens's novels about the misery and violence of London's slum dwellers. A recent opinion article in the New England Journal of Medicine called urbanization "an emerging humanitarian disaster." And urban theorist Mike Davis writes in Planet of Slums, "[N]o one knows whether such gigantic concentrations of poverty are biologically or ecologically sustainable."
But slum living today, for all its failings, is markedly better than it was in Dickens's time.
For one thing, urban quality of life now involves a lot more actual living. Through most of history, death rates in cities were so high that urban areas only maintained population levels through constant migration from the countryside. In Dickensian Manchester, for instance, the average life expectancy was just 25 years, compared to 45 years in rural Surrey. Across the world today, thanks to vaccines and underground sewage systems, average life expectancies in big cities are considerably higher than those in the countryside; in sub-Saharan Africa, cities with a population over 1 million have had infant mortality rates one-third lower than those in rural areas. …