The Anthrax Letters

Last updated January 1, 2006

Current political and economic issues succinctly explained.

More on:

Nonproliferation, Arms Control, and Disarmament

This publication is now archived.

How many letters containing anthrax were sent out in the 2001 attacks?

FBI investigators believe four letters were sent. Contaminated letters sent to the New York Post and NBC’s Tom Brokaw had a September 18, 2001, postmark. Letters to Senator Tom Daschle and Senator Patrick Leahy—postmarked October 9—carried a more potent form of anthrax. There were also confirmed anthrax cases at American Media, in Florida, and at the New York offices of CBS and ABC, though FBI investigators do not believe letters were sent to these offices.

How many people contracted anthrax from these letters?

Twenty-three, according to the Centers for Disease Control and Prevention (CDC).

How many died?


Did anyone catch anthrax who didn’t work for the media or the postal service?

Yes. Of the people who contracted anthrax, eleven worked for the postal service and eight for media organizations. (An infant visiting her mother at ABC News in New York also fell ill.) Three other people—a bookkeeper in New Jersey, a nurse in New York City, and an elderly widow in rural Connecticut—also caught anthrax. The nurse and the widow died.

How were those unconnected with the media or postal service exposed?

Probably through mail that crossed paths with an anthrax-contaminated letter, according to government investigators. Anthrax spores were found in the New Jersey bookkeeper’s mailroom. In the other two cases, no trace of anthrax was found in their mail, their homes, or anywhere they had visited before falling ill. According to postal records, however, letters headed for their neighborhoods passed through the same sorting machine as those sent to the senators, and at around the same time.

How could letters be cross-contaminated?

It is not entirely clear, but if small spores have their electrostatic charge altered so they disperse more readily—as was the case with the anthrax spores in the letters sent to the senators—they could leak out of a sealed envelope. Sorting machines may have stirred up the spores as the letters moved through.

Is one person or group sending the anthrax?

An FBI handwriting analysis indicates that the four letters and envelopes found thus far were written by one person.

More on:

Nonproliferation, Arms Control, and Disarmament


Top Stories on CFR

Censorship and Freedom of Expression

President Trump has threatened to veto a major defense funding bill over a law that protects social media companies from liability for what their users post. Why is it controversial?  

Trans-Pacific Partnership (TPP)

Though President Trump withdrew from the TPP, the remaining members of the trade pact have forged ahead with a new version, leaving the U.S. role in the Asia-Pacific in question.


Democracies should ask themselves whether forming yet another elite club of wealthy states represents the best means to counter China’s and fellow authoritarians’ digital rise.