This paper estimates indirect benefits of improved air quality induced by hydraulic fracturing, or "fracking". The recent increase in natural gas supply led to displacement of coal-fired electricity by cleaner natural gas-fired generation. Using detailed spatial panel data comprising the near universe of US power plants, we find that coal generation decreased by 28%. Further, fracking decreased local air pollution by an average of 4%. We show that benefits vary geographically; air pollution levels decreased by 35% in the most affected region. Back of the envelope calculations imply accumulated health benefits of roughly $17 billion annually.