Remi Jedwab & Adam Storeygard, "Economic and Political Factors in Infrastructure Investment: Evidence from Railroads and Roads in Africa 1960–2015" Economic History of Developing Regions 34#2 (Summer 2019) Pages: 156-208 DOI: 0.1080/20780389.2019.1627190 data covers 43 sub-Saharan countries. abstract