The Marcellus Formation straddles the New York State and Pennsylvania border, a region that shares similar geography and population demographics. However, on one side of the state line unconventional natural gas development—or fracking—is banned, while on the other side it represents a multi-billion dollar industry. New research takes advantage of this ‘natural experiment’ to examine the health impacts of fracking and found that people who live in areas with a high concentration of wells are at higher risk for heart attacks.