Let me start off this article by stating that I believe the post office does a fine job delivering the mail. Their costs are reasonable for the amount of service they provide and I appreciate all the discounts available for pre-sorting and preparing mail to the USPS' specs. With that said, now I can start getting critical and cynical.
The post office has been promoting the ZIP+4 system for several years now, and they prefer that we spray the barcodes on at the bottom of each piece. But that's not good enough anymore. They're now requesting we add a Delivery Point Bar Code (DPBC) to the end of the barcode. What we're supposed to do is take the last two digits of our street address and add those to the bar codes on our mail (not in the address, though, just in the bars). This is supposed to help our mail reach its final destination faster.
Give me a break! ZIP+4 makes sense. DPBC is a good idea, but come on, there's a limit to efficiency. Let me explain this further. ZIP codes are only 30-some years old. Before 1960 we could send a piece of mail just about anywhere in the country and, as long as we addressed it to the right city and state, we'd be pretty much assured the mail would get there in a few days. But we're a growing country and, as we expand, so does our mail flow.
Baltimore now has over half a million addresses, and sorting the mail would be next to impossible without a zoning system, or ZIP codes. But an average ZIP code in Baltimore has 12,000 homes, 1,000 businesses, and 500 or so post office boxes. Everyone gets about three pieces of mail per day, or about 40,000 pieces of mail pass through each post office every day. ZIP+4 and Carrier Route coding allows the mail to be further broken down at the post office into each mail carrier's delivery area. The extra four digits help break down the carrier's route into streets and sides of streets. This allows the carrier to easily pick up his or her pile of mail and further break the mail down to individual addresses.
Here's where we start reaching the limits of automatic sorting efficiency. Mail hits the post office and one or two machines take the mail to sort it into individual ZIP+4 trays. That's 9,999 trays for this sorting operation. Imagine the space needed to allow for this. Even if one tray can be divided into 10 different ZIP+4 areas, we're talking lots of real estate just to house the equipment and trays. Now imagine expanding this to allow enough boxes or sorting arms for 99 more locations (the DPBC) within each ZIP+4. Real estate and buildings are expensive. Further complicate this with our simple refusal to all use the same size piece of mail (#9, #10, #6, 6x9, 9x12 envelopes, boxes, parcels, etc.)
In theory, adding a DPBC after the ZIP+4, after the 5-digit ZIP code (11 digits in all) will deliver mail to the carrier ready to just be checked and delivered to us with only minor re-sorting. Add this further complication ... the sorting equipment can't read handwriting with any degree of accuracy. So all personal correspondence will still have to be either (a) sorted by hand or (b) the address will have to be manually entered into a computer so the sorting gizmos can spray those bars at the bottom of the envelope.
There's a limit to what level of efficiency we can deliver with this new-fangled equipment without driving up costs somewhere else. I can't see how adding the extra DPBC will significantly speed up the overall process. More likely, mail that carries the coding will be processed and the carriers will refuse to give any priority whatsoever to non-coded mail. ZIP codes make sense. ZIP+4 and Carrier Routes make even more sense. ZIP+4+2 for the DPBC is bordering on the absurd!