Twenty-six years before the “Great Northeast Blackout” that plunged ten million residents of the Northeast of U.S. and Canada into pitch darkness, New York City had another blackout, this one because of a lightning strike on a high-voltage transmission line. Like in 2003, an overload on one sector caused an overload on all, and nearby sectors fell like dominos.

On this day, July 13, in 1977, at around 9:30 in the evening the city of NY suddenly lost all electricity. Lights went off on roads and office buildings, trains and elevators stopped midway, and flights to LaGuardia and JFK international airports had to be rerouted to nearby ones.

Although the cause was different, the reason for the blackout’s spread from isolated event over the entire city is almost exactly the the same as in 2003: the just-in-time method of producing electricity and the increasing demand on power transmission infrastructure. As more and more electricity-hungry gadgets entered the home, power consumption increased. Transmitting more electricity over lines built according to decades-old standards becomes a tricky thing, particularly during peak times. Adding to the challenge is the difficulty for power plants to store electricity: generators often have to be calibrated to provide just enough power to meet current demand.