Artisanal and Small-Scale Mines in Africa: Where, When and Why

As demand for critical minerals accelerates with the energy transition, artisanal and small-scale mining (ASM) has emerged as a key but poorly understood source of supply. We construct the first continental-scale panel of mining activity in Sub-Saharan Africa by applying supervised deep-learning methods to satellite imagery, identifying over 50,000 mining sites across 39 countries and reconstructing monthly activity from 2000 to 2019. We document three main findings. First, mining location follows strong market-access gradients with pronounced non-linearities: proximity to ports raises mining probability within 200 km, but this premium reverses at intermediate distances and re-emerges only in the most remote areas -- consistent with distance from urban centers proxying for weaker state reach and lower monitoring of informal activity. Second, entry responds rapidly to commodity price shocks, indicating that ASM operates as an elastic margin of mineral supply; over time, however, its relationship with industrial mining shifts from complementarity to a reallocation of artisanal activity away from industrial sites. Third, agricultural shocks induce entry into ASM, but spatial labor mobility attenuates local responses, pointing to strong congestion effects. Together, these results position ASM as a central yet spatially constrained adjustment margin in global critical mineral supply.