Abstract

This paper develops a GIS raster of transport cost in precolonial Africa, a fundamental constraint on long-term political and economic development. The technology set includes walking and canoe travel. The end product is a Cell-Cost raster that combines walking speeds over a variety of terrains (using the Waldo Tobbler Hiking Function as the vertical factor of a DEM elevation projection) and canoe speeds along rivers of different velocities (using The Major River Basins of the World, classified by mean annual discharge and estimates of river velocity developed from afriv). As a demonstration, the Path Distance Tool in ArcGIS is used to estimate the least-cost travel time from anywhere on the continent to the nearest “coastal” slave port between 1500 and 1850. The resulting estimates of travel time are used to identify the effects of the international slave trade shocks on African labor institutions (slavery), family structure (polygyny), agricultural technology (plow) and religious belief (High God). Simple estimates of straight-line distance are shown to have no explanatory power in this context.