West Africa was - conceived - for the most part by the colonizers seeking suppliers of agricultural raw materials. The Office du Niger (initially set up for cotton), the groundnut basins in Senegal and northern Nigeria, cotton basins, rubber tree and oil palm plantations were responsible for shaping the rural landscape, fostering the development of towns, redistributing the population and sometimes even defining borders of future nations states. Cocoa and coffee are emblematic of this history. Often considered inseparable, grown in the same areas, both dependent on the London and New York stock exchanges, subject to speculative global markets, they are two topic-specific chapters of the Atlas on Regional Integration in West Africa.
Bastide et al. (Mon,) studied this question.