This paper provides a detailed descriptive analysis of patterns of urbanization across Sub-Saharan Africa for the  year circa 2015. Despite the rapidity and importance of  Sub-Saharan Africa’s urbanization, little is known about  the anatomy of patterns of urbanization across the region  due to a lack of detailed and accurate official data on urban  settlements and populations. To address this gap, the paper  applies a modified version of the “dartboard” algorithm  to high-resolution gridded population data for the region,  which is derived from digitized maps of the footprints  of all buildings in the region from very high-resolution  satellite imagery. This allows for a consistent definition of  urban areas across all countries in the region, overcoming  the measurement problems that arise from relying on official definitions of urban areas, which vary markedly across  countries. Using this definition, the paper presents evidence  on key empirical regularities that are related to disparities  across the urban hierarchies, such as the extent of urban  primacy and Zipf’s law, as well as on the internal structures of cities, such as population density gradients and  the number of centers that cities possess. The paper also  analyzes how these characteristics are related to key country  characteristics. Finally, the paper compares the results with  those that arise from the use of an alternative definition of  urban areas—the degree of urbanization.