On a late Thursday afternoon in the summer of 2003, everything turned off. As this week’s Retro Report video illustrates, in the span of a few minutes, the biggest power outage in United States history brought swaths of the Northeast, the Midwest and Canada to a standstill. Around 50 million people were left without power. In the days and weeks that followed, reporters and investigators raced to pinpoint the source of the outage, while larger questions swirled about the stability of the power grid in the 21st century. Here, a Times reporter who covers energy technology reflects on that day and the changes that resulted.

When the lights went out for 50 million people on Aug. 14, 2003, most of them knew only that they themselves had lost electricity, not that a tightly knit system had been ripped apart all the way from Detroit to Toronto to New York City. Even the people in electric control centers were confused; some of those in the Midwest knew the magnitude of the problem only because they were watching CNN, which showed a blacked-out Times Square.

I had been at the Indian Point nuclear plant that morning to report an article about handling nuclear waste. By 4 P.M. I was in southern Westchester in my parents’ kitchen, unplugging the telephone so I could connect it to my laptop modem and file to The Times. As I connected the phone line to the modem, the lights went out.

“Matthew, what have you done?” my mother asked. In daylight, it’s hard to tell that the whole neighborhood has been switched off, but a battery-powered radio tuned to an AM station (then popular — it was still 2003) confirmed that New York City was also dark.