Where Do Africa’s Growth Corridors Actually Emerge? Comparing Policy Corridors with Satellite-Observed Growth

Development corridors are widely promoted as instruments of African regional integration and urban transformation, yet whether planned corridors actually become observable growth corridors remains rarely tested at the continental scale. Without imposing a predefined corridor list, we identify linear growth corridors across 50 African countries from 2010–2020 built-up expansion and 2012–2020 nighttime-light change using spatial clustering and spatial autocorrelation, compare them with policy corridors, and estimate grid- and corridor-level association models to examine the factors behind corridor emergence. The results characterize the spatial patterns of 82 main corridors and 320 sub-corridors: high-growth cells are strongly transport-aligned, with a median distance to the main transport network of 0.90 km versus 5.34 km for background cells; roads carry continuous growth, whereas railways form a station-centered secondary axis. Policy corridors cover 14.6% of land cells and capture 43.3% of built-up growth and 61.5% of light growth within 25 km, but main-corridor length overlap is only 42.4%, including both planned-but-weakly-grown and grown-but-unplanned mismatches. The results show that corridor emergence is shaped mainly by continuous road accessibility, inherited settlement, port and airport gateways, and security conditions. Policy corridors should therefore be treated as potential directions, with resources prioritized for secondary-road and gateway connections in weak-correspondence corridors rather than extending line extents.