In Africa today, in a majority of cities and towns, a twin development process is occurring wherein formal and informal cities are developing in parallel. In a majority of countries, informal cities, which are multidimensional in structure and scope, are predominating and transforming the urban landscape and environment. Cities are essentially being built back to front, with development taking place before the formulation of planning strategies and the implementation of control and management systems—building structures first and services afterward. This reversed development approach is also reflected in the housing development process, with the poor playing a leading role as the construction project manager, laborer, and finance provider. Moreover, most African cities and towns today are characterized by a dual economy of formal and informal sectors, with the vast majority of the urban population operating within the informal economy, outside existing regulatory frameworks. The development, expansion, and proliferation of slums and informal settlements, in which the majority of urban poor households live and work, are the most conspicuous manifestation of this reality.

T his multidimensional informality (in land tenure, housing, servicing, and employment) has given rise to a prevailing urban condition that is evident in cities and towns across the continent, which Pieterse (2013) describes as the challenge of “slum urbanism.” According to Pieterse, slum urbanism is driven by a self-fulfilling cycle that drives urban development patterns in most sub-Saharan African cities, as illustrated in Fig.  6.1. Hence, as the continent’s urban population doubles in one generation, it can be expected that slum dwellers will continue to develop their own cities because the state and the formal market do not yet have the capacity to address the escalating demand for land, housing, and services. In 2012, an estimated 863 million urban residents worldwide lived in slum conditions, compared with 760 million in 2000 and 650 million in 1990. The proportion of the urban population living in slum conditions in urban areas was particularly high in sub-Saharan Africa (62 percent) and, to a lesser extent, in Southern Asia (35 percent), compared with 24 percent in Latin America and the Caribbean, and 13 percent in North Africa (UN-Habitat 2014b).