A massive blackout hit the northeastern US and Canada
On this day · 14 August 2003
On August 14, 2003, a cascading grid failure plunged roughly 50 million people into darkness across two countries.
At about 4:10 p.m. on August 14, 2003, the lights went out across a vast swath of the northeastern United States and southern Canada. Roughly 50 million people lost power in a single afternoon, in what remains one of the worst blackouts in North American history.
The outage spread from New York, Massachusetts, and New Jersey west to Michigan, and from Ohio north to Toronto and Ottawa. A local problem in Ohio—overloaded lines and a control-room alarm failure—cascaded across the grid faster than operators could react.
A handful of overlooked warnings in one control room rolled outward until a whole region went dark.
Most areas had power back within hours, though full restoration in places like New York City and Toronto took until August 16. The episode exposed how fragile a tightly interconnected grid can be, and reshaped how reliability rules are written and enforced.
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