The statistical records that have been collected, systematized and synthesized here provide a quantitative basis to challenge and shape existing narratives on African economic development from the nineteenth-twentieth centuries. However, the history of counting and registering people is as old as documented history – with taxation, it is a central part of a state’s effort to govern. The word “statistics” itself derives from “state” and statistical records are primarily the historical footprint of states. We see what the states knew about themselves, what they cared to find out, and their chosen projected image. In this chapter, we give an overview of the history of census taking in Africa, and further evaluate the basis of the architecture of knowledge that colonial and postcolonial states have left behind. It is particularly important to clarify what kind of questions the state records can answer, and where other evidence sources will have to be used, as this chapter sets the ground for the empirical analysis presented in the three following chapters. The chapter concludes with a view toward further research, in particular the use of other data sources, to expand “new economic history” beyond the colonial period and the use of the colonial records.