A new idea of measuring economic growth is proposed in a recent paper: satellite data on lights at night. This new measurement can be readily applied to countries as well as to cities. What's more, the framework can be applied to countries with the lowest quality income data, resulting in estimates of growth that differ substantially from established estimates. A longstanding debate is also considered: do increases in local agricultural productivity increase city incomes? For African cities, we find that exogenous agricultural productivity shocks (high rainfall years) have substantial effects on local urban economic activity.