[Keith in Iowa]

About the only places I can think of that might have had a strain on file is the USDA's National Animal Disease Lab in Ames, and perhaps the vet school at Iowa State University...

[crypt2k]

Manmade vectors for anthrax spore dust are many and varied. One possible vector begins at the printing presses of newpapers and magazines. Dust trapped between pages could infect the unspecting subscriber or supermarket checkout line browser.

[Ada Coddington]

About the only places I can think of that might have had a strain on file is the USDA's National Animal Disease Lab in Ames, and perhaps the vet school at Iowa State University...

I doubt the hijackers had access to that supply, or at least direct access.