What are you smoking?
After the 3 gram micro attack, we have spent over 100 million on decontamination, and two major USPS mail centers are STILL closed as unsafe, including one a mile from the US Capitol.
After a 3 gram warning attack!
Tell me how we will clean up after a 100,000 gram (100 kilo) attack on our entire USPS, FEDEX and UPS systems? Plus airports and subways?
How does that work?
By your "100# equals one day delay" calculation, the 3 gram warning shot should have been cleaned up in about 7 seconds.
But after a year and a half and tens of millions each in cleanup costs, those postal centers are STILL CLOSED.
Please explain this discrepency, I must be too dim to perceive your mathematics.
If you send in a letter to the FAA in Oklahoma, it takes an extra 3 weeks right now as all of their mail is being re-routed, irradiated, then sent back to OK. 3 weeks is fine for bureaucrats, but civilians will demand faster irradiations (and that's not a technical hurdle, just a matter of money).
Likewise, ground deliveries of produce, goods, and other daily business items will all have a full day added to them (if they leave a single city) as they get inspected by various feds after an attack such as you describe.
Ports would also get hit with delays, and I would suspect that all ships would begin being inspected at our territorial water limit rather than in harbors.