The poorest urban populations, however, are probably found in Luanda, Maputo, Kinshasa, and Cochabamba (Bolivia), where two-thirds or more of residents earn less than the cost of their minimum required daily nutrition.¹⁷ In Luanda, where one quarter of the households have per capita consumptions of less than 75 cents per day, child mortality (under five) was a horrifying 320 per thousand in 1993 – the highest in the world.¹⁸

      Not all urban poor, to be sure, live in slums, nor are all slum-dwellers poor; indeed, The Challenge of Slums underlines that in some cities the majority of the poor actually live outside the slums stricto sensu.¹⁹ Although the two categories obviously overlap in their majority, the number of urban poor is considerably greater: at least one-half of the world’s urban population as defined by relative national poverty thresholds.²⁰ Approximately one quarter of urbanites (as surveyed in 1988), moreover, live in barely imaginable “absolute” poverty – somehow surviving on one dollar or less per day.²¹ If UN data are accurate, the household per-capita income differential between a rich city like Seattle and a very poor city like Ibadan is as great as 739-to-1 – an incredible inequality.²²

      Accurate statistics are in fact difficult to come by, because poor and slum populations are often deliberately and sometimes massively under-counted by officials. In the late 1980s, for example, Bangkok had an official poverty rate of only 5 percent, yet surveys found nearly a quarter of the population (1.16 million) living in 1000 slums and squatter camps.²³ Likewise the government of Mexico claimed in the 1990s that only one in ten urbanites was truly poor, despite uncontested UN data that showed nearly 40 percent living on less than $2 per day.²⁴ Indonesian and Malaysian statistics are also notorious for disguising urban poverty. The official figure for Jakarta, where most researchers estimate that one quarter of the population are poor kampung dwellers, is simply absurd: less than 5 percent.²⁵ In Malaysia, geographer Jonathan Rigg complains that the official poverty line “fails to take account of the higher cost of urban living” and deliberately undercounts the Chinese poor.²⁶ Urban sociologist Erhard Berner, meanwhile, believes that poverty estimates for Manila are purposefully obfuscated, and that at least one-eighth of the slum population is uncounted.²⁷

      A Slum Typology

      There are probably more than 200,000 slums on earth, ranging in population from a few hundred to more than a million people. The five great metropolises of South Asia (Karachi, Mumbai, Delhi, Kolkata, and Dhaka) alone contain about 15,000 distinct slum communities whose total population exceeds 20 million. “Megaslums” arise when shantytowns and squatter communities merge in continuous belts of informal housing and poverty, usually on the urban periphery. Mexico City, for example, in 1992 had an estimated 6.6 million low-income people living contiguously in 348 square kilometers of informal housing.²⁸ Most of the poor in Lima, likewise, live in three great peripheral conos radiating from the central city; such huge spatial concentrations of urban poverty are also common in Africa and the Middle East. In South Asia, on the other hand, the urban poor tend to live in a much larger number of distinct slums more widely dispersed throughout the urban fabric in patterns with an almost fractal complexity. In Kolkata, for instance, thousands of thika bustees – 9 hutments of five huts each, with 45-square-meter rooms shared, on average, by an incredible 13.4 people – are intermixed with a variety of other residential statuses and landuses.²⁹ In Dhaka, it probably makes more sense to consider the nonslum areas as enclaves in an overwhelming matrix of extreme poverty.

      Although some slums have long histories – Rio de Janeiro’s first favela, Morro de Providencia, was founded in the 1880s – most megaslums have grown up since the 1960s. Ciudad Nezahualcóyotl, for example, had barely 10,000 residents in 1957; today this poor suburb of Mexico City has three million inhabitants. Sprawling Manshiet Nasr, outside Cairo, originated as a camp for construction workers building the suburb of Nasr City in the 1960s; while Karachi’s vast hill slum of Orangi/Baldia, with its mixed population of Moslem refugees from India and Pathans from the Afghan border, was founded in 1965. Villa El Salvador – one of Lima’s biggest barriadas – was established in 1971 under the sponsorship of Peru’s military government, and within a few years had a population of more than 300,000.

      Everywhere in the Third World, housing choice is a hard calculus of confusing trade-offs. As the anarchist architect John Turner famously pointed out, “Housing is a verb.” The urban poor have to solve a complex equation as they try to optimize housing cost, tenure security, quality of shelter, journey to work, and sometimes, personal safety. For some people, including many pavement-dwellers, a location near a job – say, in a produce market or train station – is even more important than a roof. For others, free or nearly free land is worth epic commutes from the edge to the center. And for everyone the worst situation is a bad, expensive location without municipal services or security of tenure. In Turner’s celebrated model, based on his work in Peru in the 1960s, rural migrants first move from the province to the city center – location at any price – to find jobs; then, with employment security, they move to the periphery, where ownership is attainable. This progress from (in his terminology) “bridgeheader” to “consolidator” is, of course, an idealization that may only reflect a historically transient situation in one continent or country.³⁶

Figure 7. 30 Largest Megaslums (2005)³⁰