Yes, the PO is being used as the final destination delivery, while the items are shipped by others(DHL,UPS,Fedex, and now Amazon) from the sender to that final office. So the USPS tracking always shows not accepted by them for much of the trip(the tracking).
In Sevierville we have about two USPS trucks come each day from the main Knoxville office. But the UPS, Fedex, and Amazon bring parcels directly to our office. I think there's one for UPS and Fedex each day, but Amazon comes three times or more.
The back ups in the PO I'm told are mainly in the large distribution centers, where they do have more parking space to "store" trucks there. The smaller offices can't do that, they are forced to handle it. I heard that there were 29 trucks at one time parked in Chattanooga, which I didn't know was one of those big distribution centers. Knoxville isn't really, but it covers all surrounding counties, 377, 378, and 379(Knoxville) offices.
The world is on fire right now, people have plenty of money to spend, and everyone thinks the government is going to solve everything. A lot of people don't seem to be worried, yet they are scared of the virus, because the government convinced them it's terrible.