IIRC, the idea wa floated that the USPS woud deliver Cipro in case of an Anthrax attack (don’t know what became of it)
The shipments are probably sitting in the back of some postal truck, covered by the postal worker’s porn mags and Mickey D’s wrappers.
That’ll work well until the first jeep is swarmed by mobs like a bag of rice dropped from a helicopter into Haiti.