From Your Doorstep
The mail delivery process begins at your mailbox, of course. Once your envelope is sealed, addressed and has a stamp upon it, the mail carrier will pick it up, either at your doorstep or another postal box in which you place it. The mail carrier puts it on his truck and takes it to the local post office. Each city in the United States has its own post office where the mail is loaded onto the larger U.S. Postal Service trucks for shipment to a distribution center. Most cities in the U.S. are within a four-hour drive of a regional distribution center. These decentralized hubs make the process much faster.
At the Distribution Hub
Once your mail reaches the regional distribution center, your handwriting or address label is read into a computer that converts that into a barcode. The barcode is stamped onto the front of the envelope in fluorescent ink and the stamps are marked through so they can not be reused. The envelopes move down a conveyor belt and the fluorescent ink on each individual piece of mail is scanned by a sorting machine. Based on the area of the country that the piece of mail is headed to, it is sorted into bins that are then loaded onto trucks or planes for transportation to the regional distribution center in which the target ZIP code is located.
Out for Delivery
Once the piece of mail reaches its target region, it is again sorted into trays labeled with individual ZIP codes within that region. Each mail carrier is assigned specific routes and ZIP codes, and they are mapped to ensure maximum efficiency. The properly sorted mail is loaded into the truck responsible for the postal code marked on the envelope, and it is up to the individual mail carrier to ensure that it gets to the right end-user mailbox.