The question was a reflex: Is it terror? The power failure at the start of rush hour put tens of millions of people in the U.S. and Canada on edge. Radio and TV news reports soon allayed the fears, conveying comforting assurances from government officials. But they began to raise new questions as the disasters breathtaking scope became clear. The blackout of 2003 was the worst in North American history.
On the afternoon of Aug. 14, a series of transmission lines in Ohio and Michigan gradually tripped off. As each lines current was rerouted, pressure on the system built. The tempo of trips grew after 3 p.m. Shortly after 4 p.m., the failures cascaded like floodwater topping a dam, overwhelming defenses and washing over eight states and two provinces.