B-roll of USPS trucks unloading letters at a letter processing plant.
At the plant, the letters are fed through a barcode sorter that sorts the letter to the particular carrier who will deliver it. The delivery barcode sorter also arranges that carrier’s letters into the order of delivery.
B-roll of letters being sorted by machine at a letter processing plant and then stacked in trays with other mail by ZIP Code range.
Trays are then taken to the airport to fly across the country for final delivery.
After the plane lands at its destination, postal workers take the tray containing the letters to another mail processing plant that serves a Post Office, station, or branch that will deliver the letter.