Effective targeting of social policies and their rigorous evaluation requires relevant and accurate data. With the majority of the world’s poor depending on agriculture and informal businesses for their livelihoods, information on these sectors is particularly valuable. I use high-frequency satellite imagery to develop a novel method mapping rural periodic markets across large geographies and tracking activity within them in real-time. I show that the method accurately detects existing markets and that measured activity not only correlates with alternative indicators, but also expands their temporal and geographical detail. Focusing on Kenya and Ethiopia, I present an application of the method to the effects of lockdowns and violent conflict on market activity.