A mechanical fault knocked a 230kV transmission line offline in Northern Virginia’s “Data Center Alley,” causing a dense cluster of AI data centers to instantaneously switch to backup generation. The abrupt, simultaneous removal of roughly 3 gigawatts of demand sent a voltage and frequency disturbance rippling across the entire Eastern Interconnection, an event sensor networks detected as far away as Chicago and Miami. Grid operator PJM and Dominion Energy stabilized the disturbance within about ten minutes without a wider blackout, but the incident intensified regulatory scrutiny of how concentrated AI data center demand can amplify routine grid faults.