# 1   Introduction

Today more than half the world’s population lives in urban areas. The transition from a rural world to an urban one has been led by the rapid, dramatic, and difficult urbanization in the developing world. The shift has been difficult, not least because cities in the developing world have neither been able to plan for nor to keep pace with this transformation. Consequently, more and more urban residents live in unplanned, squalid settlements that lack access even to basic services such as piped water, sanitation, drainage, and electricity. The situation is deemed so alarming that one analyst describes Earth as a “planet of slums” (Davis 2006).

Despite the magnitude of urbanization, and despite widespread agreement on its significance, however, we lack answers to fundamental questions about the lives of urban residents—especially slum residents—in the developing world. This gap is particularly pronounced in Africa, which is both the most rapidly urbanizing and the poorest region of the world (UNFPA 2007).

In this study, we empirically examine development and living conditions in slums. What levels of infrastructure services do slum residents tolerate? How do these levels vary, within and across cities? What explains these variations? Drawing on random samples of slum residents in Dakar, Johannesburg, and Nairobi, this paper explores these questions and offers some novel, provocative, and policy-relevant empirical evidence. Our main findings are as follows:

- The cities in our sample exhibit heterogeneity—slums in the three cities differ dramatically from each other on nearly every development indicator that we examined. This finding belies the notion that most African cities face a more or less similar slum problem. By extension, it also challenges the idea that one approach to—or template for—the upgrading of slums can work in all African cities.

- In comparing the three cities, it is striking that measures of income and human capital correlate poorly with infrastructure access and quality of living conditions. In Dakar, slum residents have fairly decent living conditions, even though they have low levels of educational attainment and high levels of income poverty. By contrast, in Nairobi slum’s living conditions are appalling although most slum residents have jobs and a comparatively high level of education. Although far from conclusive, this evidence suggests that reduction in income poverty and improvements in human development do _not automatically_ translate into improved infrastructure access and quality of living conditions for the urban poor. Future research will want to focus on the factors that explain the variation—and facilitate improvements—in quality of living conditions.

- Within each city, and even within a given slum, we again find heterogeneity. First, we were encouraged to find that not all slum households are poor. Second, slum residents have heterogeneous living conditions, depending on their welfare/poverty status and on the neighborhood in which they reside.

- In comparing poor and nonpoor slum residents within a given city, we find the poor often lagging behind their nonpoor neighbors in access to some basic infrastructure and they endure worse living conditions. For instance, in both Nairobi and Dakar, the poor are systematically less likely to have