You’ve probably heard it before: that 90% of Americans would die within a year of an EMP attack. It’s one of the most quoted numbers in all of preparedness.



But that number didn’t come from a study or model. It came from a single sentence in a 2005 Senate hearing. It wasn’t a forecast—it was one extreme of a range, from no deaths to full collapse.



Still, over time, the 90% death rate became gospel. And too many people now treat it as an inevitable outcome, especially in the prepper community.



I’m not an EMP physicist—and I’m not saying it couldn’t happen. I’m saying it was never a guarantee. Planning for the worst is smart, but regurgitating the 90% as a guaranteed outcome isn't. It's one possibility among many EMP possibilities, and smart preparedness is built on facts, not assumptions.



This article walks through where the number came from, how it spread, and why context—and critical thinking—still matter.







TL;DRThe 90% EMP death toll claim came from a 2005 Senate hearing as a worst-case scenario—one extreme on a wide range from no deaths to societal collapse—it was never supported by scientific modeling or data.











Quick Look at What You’ll Learn

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What the 90% EMP Statistic Refers ToWhere the 90% Number Did Not Come FromWhere the 90% EMP Statistic Actually StartedWhy the 90% Figure StuckIs There Scientific Support for the 90% Number?What a Large-Scale EMP Could Lead ToThe Bottom Line on the EMP 90% StatisticFAQ: EMP and the 90% StatisticAdditional Resources













What the 90% EMP Statistic Refers To

The 90% number refers to a projected worst-case scenario in which a high-altitude nuclear EMP detonation disables the U.S. power grid, leading to a cascading collapse of critical infrastructure.



Under this scenario, the country would lose access to:



Electricity (long-term grid failure)

Transportation and fuel delivery

Water treatment and distribution

Food production and refrigeration

Healthcare systems and medications



The 90% figure estimates how many Americans could die within 12 months due to starvation, disease, exposure, and civil breakdown, not the EMP blast itself.







Where the 90% Number Did Not Come From



Not from William Forstchen’s One Second After

The 2009 novel One Second After by William Forstchen helped popularize the severity of EMP threats in fiction. It depicts a U.S. town descending into collapse after an EMP, with a death toll in the tens of millions.



However, despite what some believe, the novel never mentions the 90% statistic. Many people assume it originated here because the book was cited during congressional hearings, but that is incorrect.

Not from the EMP Commission’s Official Reports

In 2008, during a House Armed Services Committee hearing on the EMP threat, Representative Roscoe Bartlett asked if the mass fatality scenario in One Second After was realistic. Dr. William Graham, Chairman of the EMP Commission, replied:

It’s in the range of possibilities.

That exchange introduced the 90% figure into the congressional record during a 2008 House Armed Services Committee hearing, not in the 2008 EMP Commission report itself. In fact, the EMP Commission never published a study or model confirming that number in any of its official reports. source







Where the 90% EMP Statistic Actually Started

The earliest known use of the 90% figure came in March 2005. During a U.S. Senate hearing on the EMP threat, physicist Dr. Lowell Wood testified:

The parameter space is kind of as big as all outdoors… It goes all the way from… a blackout, with no loss of life… to something which would literally destroy the American na...