Ethnic Geography and the Colonial Design of Administrative Units in Sub-Saharan Africa

Subnational administrative units are fundamental to territorial states and their political topography, but we know little about how their borders are designed. I argue that indirect rulers engage in preservation by ethnically aligning administrative borders, which empowers peripheral actors. In contrast, centralizing governments disrupt ethnic groups and their ability for collective action by splitting groups (dismemberment) and/or creating diverse units (suffocation). I test this argument by studying colonial administrative unit designs in Sub-Saharan Africa. I contrast indirect British with more direct French colonial rule and use new historical data on administrative borders and ethnic geography. Modeling subnational borders with a probabilistic spatial partition model, I find strong positive associations with ethnic boundaries under British compared to French rule, which realized more extensive ethnic dismemberment but not suffocation. The results shed light on colonial administrative unit designs, thus highlighting the importance of unit endogeneity more broadly.