West African poverty forced a pooled federal structure to justify colonial costs

Evidence

The relative poverty of certain West African territories was another decisive factor encouraging Paris to adopt a federal structure for West Africa. Only by pooling the resources of all their colonies could the territory as a whole, and the Western Sudan in particular, prosper and thereby justify the expenses involved in acquiring the colony in the first place. … In addition to coordinating military and economic policy in West Africa, it would be responsible for raising sufficient revenues locally to secure loans for a modern transportation network linking the savanna to the coast, whose design and execution it was also to oversee. — Alice L. Conklin, A Mission to Civilize_ The Republican…, 127