Northeast blackout of 2003
major power outage in August 2003 in North America
The Northeast blackout of 2003 was a widespread power outage throughout parts of the Northeastern and Midwestern United States, and most parts of the Canadian province of Ontario on Thursday, August 14, 2003, beginning just after 4:10 p.m. EDT.
Most places restored power by midnight (within 7 hours), some as early as 6 p.m. on August 14 (within 2 hours), while the New York City Subway resumed limited services around 8 p.m. Full power was restored to New York City and parts of Toronto on August 16. At the time, it was the world's second most widespread blackout in history, after the 1999 Southern Brazil blackout. The outage, which was much more widespread than the Northeast blackout of 1965, affected an estimated 55 million people, including 10 million people in southern and central Ontario and 45 million people in eight U.S. states.
The blackout was due to a software bug in the alarm system at the control room of FirstEnergy, which rendered operators unaware of the need to redistribute load after overloaded transmission lines dropped in voltage. What should have been a manageable local blackout cascaded into the collapse of much of the Northeast regional electricity distribution system.
Immediate impact
According to the New York Independent System Operator (NYISO)—the ISO, responsible for managing the New York state power grid—a 3,500 megawatt power surge (towards Ontario) affected the transmission grid at 4:10:39 p.m. EDT.
For the next 30 minutes, until 4:40 p.m.
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