Experts say a continent-wide failure would require some kind of physical damage to the power system: something like a massive solar flare -- the so-called "Carrington event" of 1859 -- that caused telegraph wires to fry worldwide and led to visible auroras in places like Cuba and Jamaica.
"There has been some modeling that says (a similar event today) could cause significant damage to electronics," said Mark Weatherford, principal at the Chertoff Group and former security chief for the North American Electric Reliability Corporation, a non-profit regulatory group responsible for maintain power.
"This is something that has not gone unnoticed," Weatherford said. "Industry and government have been very active to understand the implications that the threat would cause."
In recent years, manufacturers have looked at ways to protect transformers from solar events, shunting high-voltage lines into the ground so they aren't damaged and figuring out ways to isolate troubled substations from the main grid.
Protecting against cyberattacks is an ongoing battle. Just last week, a new report by Symantec warned of serious threats to electric grids from "Dragonfly," a group of hackers likely based in Eastern Europe who have launched malware to disrupt power supplies, industrial control systems and other kinds of infrastructure. Weatherford said the weak link is the companies that provide software to utilities.
The hackers infiltrated industrial control vendors, who then issued updates and patches with contaminated software that were uploaded by utilities.
"It is a concern and there's a lot of people looking into this right now," Weatherford said.
Thinking about the unthinkable -- at least when it comes to a massive power outage -- is a good exercise for engineers like Iowa State's Dobson. He says that the United States has ignored fixing infrastructure like the power grid for too long, even though the possibility of a widespread catastrophe is low.
"The power grid is a complex machine, and everything east of the Rockies is all tied together," Dobson said. "There's good reason to have such a large power grid, to back each other up, but it also has a vulnerability and occasionally you can have a cascading failure."
Weatherford says the U.S. grid is not likely to fail. There are too many ways to isolate trouble spots. But if things go south, you might want to consider moving to Texas. The Texas power grid is self-sustainable for power generation and distribution.
"Texas," Weatherford said, "could probably disconnect and be fine on their own."