The development of the African system of cities

Sub-Saharan Africa has urbanised at tremendous speed over the last half century, in a process that has dramatically reshaped the economic and spatial profile of the region. Simultaneously, it has challenged much of the conventional empirical wisdom about how and why people move to cities. As we show in this article, the traditional view that countries urbanise alongside struc-tural transformation is challenged in Africa, where urbanisation occurs despite low productivity in agriculture, very limited industrialisation, and a high share of primary sector employment across the urban hierarchy. There appear to be large household income gaps between urban and rural areas inducing migration, and these income premiums apply equally well to farm and non-farm families. Looking across the urban hierarchy, we also discuss how urban primacy can be problematic for economic growth in Africa, how secondary cities are lagging in industrial development, and how growth of employment in tradable services may signal a different path to structural transformation in Africa