Considering that a tree's touching an Oregon transmission line in 1996 sparked a blackout stretching from Mexico to Canada, it's not hard to imagine how coordinated attacks on the power grid could wreak continent-wide havoc. But within five years, new computer models could have the ability to respond to disasters in real time, throwing switches and rerouting power as repercussions spread. And that could help North America's interconnected grids protect themselves in the face of cascading failures, whether touched off by trees or terrorists.

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