Perpetual Motion: Human Mobility and Spatial Frictions in Three African Countries

Recent literature points to the importance in developing countries of spatial and sectoral gaps in wages and living standards. These gaps seemingly imply frictions to human mobility. In this paper, we present new evidence on mobility within three African countries. We use a novel data source that provides highly detailed location data on more than one million smartphone devices across three large African countries for an entire year. This allows us to examine high-frequency mobility patterns for a subset of people for whom we can determine home locations confidently. The data offer insights into patterns of mobility, with corresponding implications for the nature and extent of mobility frictions. In particular, our data point to the ubiquity of relatively high-frequency journeys within countries -- i.e., visits. We observe that many users travel to relatively distant within-country locations, with big cities acting as particularly attractive magnets. We develop a conceptual framework that characterizes the role of visits for individuals and provides a number of testable predictions that are consistent with the movement patterns that we observe in the data. The analysis suggests that distance-linked mobility costs are not so high as to discourage travel. In fact, travel enables users to benefit from the opportunities that large cities provide, without having to incur the costs of relocation. The frictions sustaining spatial and sectoral gaps thus seem to reflect deep fixed costs associated with the dislocations of migration and sectoral change, rather than the direct costs of movement.