REGIONAL STRUCTURE IN SUB-SAHARAN AFRICA

The urban hierarchies of 280 subnational regions of sub-Saharan Africa are shown to be systematically related to ecological and economic indicators all across Africa, despite that continent's cultural and ecological diversity. Using data from detailed maps of Africa, it appears that urban hierarchy, indexed by the number of cities with a population of 20,000 or more, correlates with the number of towns, the population of the largest place, the population of the region, density, the number of industries (both agricultural and general), and even ecological features like lakes, forests and dams. Additionally, and surprisingly, the number of different agricultural export crops in the region and the number of different minerals that are exploited correlate with the number of cities. Regression analysis of cities and towns within zones, defined by distance from the coast, clarifies the determinants of hierarchy levels.