Between 1935 and 1940 the Italians built an extensive road network to facilitate the occupation of Ethiopia and secure control over the Horn of Africa, but were expelled in 1941. This provides a unique case study to examine the long-run effect of cheap transport networks on the concentration of economic activity in developing countries. The results show that cells located next to Italian paved roads are significantly richer today and that the relationship is causal. Persistence is explained by a combination of direct and indirect mechanisms: colonial roads attracted economic activity through lower transport costs until 1960. After that date, the advantage of treated locations persisted only indirectly through increasing returns to scale
