An anonymous reader writes: A project called 'Gridstrike' found that free and publicly available information can be used to determine the most critical electric substations in the US, which if attacked, could result in a nationwide blackout. Researchers from iSIGHT Partners used a combination of publicly available transmission substation information, maps, Google Earth, and grid congestion documentation, and drew correlations among the substations that serve the top ten cities in the US. They ID'ed 15 substations that if attacked and knocked offline would result in a nationwide blackout, they say. Their research took the spin of whether a homegrown terror group with little funding could get this crucial information. The study was inspired by the 2013 Federal Energy Regulatory Commission (FERC) study in 2013 that found that attacks on just nine electric substations in the U.S. could cause a blackout across the entire grid.