  Despite global progress in reducing extreme poverty, stubborn pockets remain,
often in remote and fragile regions. A fundamental obstacle to further progress
is that remoteness and fragility also constrain data collection on economic
conditions. We present a new approach to monitor remote economies using
satellite images that capture activity at periodic markets, focal points for
rural trade throughout history and much of the world today. We describe how to
detect markets without pre-existing maps and how to construct an up-to-weekly
measure of their activity. We show that we successfully detect markets and that
activity correlates with other measures of economic conditions, captures
seasonal patterns, and responds to local weather and conflict. The imagery's
global availability and high frequency enable real-time monitoring independent
of ground conditions.
