A ZIP code is a numerical system that the U.S. Postal Service (USPS) has used since 1963. ZIP stands for “zoning improvement plan”, and it was chosen because it was determined that it would ensure mail could just “zip” through. In 1983, the +4 code was added, which come after a hyphen after the original 5-digit zip code. So why is there 9 digit zip codes?
A Brief History:
Before looking at why is there 9 digit zip codes, it is important to understand the history of these codes. The name was registered by USPS as a servicemark, but this has since expired. In 1943, the then U.S. Post Office Department (USPOD) decided that larger cities should have their own postal zones. By the 1960s, however, it was clear that this should be more organized.
On July 1, 1963, non-mandatory zip codes, as we know them today, were introduced. Publication 59: Abbreviations for Use with ZIP Code was released by the USPOD, explaining what the different abbreviations mean and where they are. This has not changed at all ever since, except for Nebraska, which was NB and because NE in 1969, as requested by the Canadian postal administration (NB is New Burnswick).
It is believed that the man who made this all possible was Robert Moon. In 1944, he worked as a postal inspector and suggested that the zip code be used. However, he is only credited with the first three digits, which is what allows mail to be sorted to the relevant central mail processing office. The next two digits refer to the actual post office itself. By 1967, including a zip code became mandatory for all 2nd and 3rd class bulk mailers, and the rest of the country adopted it rapidly thereafter. In 1971, the White House started to include zip codes on their envelopes, when Dick Baumbach, reported for the Elmira Star Gazette, noted they had not yet done so.
Why Is There 9 Digit Zip Codes?
In 1983, the USPS developed the “zip +4 code”. This system uses the same standard zip code, but adds a further four digits to it. This identifies a more specific geographical area within the area of the post office. For instance, it can pinpoint to exact units, specific post boxes, streets, floors in apartment buildings, and so on.
The USPS tried to promote using the zip +4 code, but people seemed very resistant to it. To this day, therefore, it is still not mandatory to use it. That said, the reality is also that, if the full 9 digit code is used, the mail item has to be handled a lot less, which also reduces the chance of human error. Interestingly, while the USPS was at first nothing short of innovative by using zip codes, they now lag far behind the rest of the world, where zip codes point to very small geographical areas. In so doing, postal workers and post offices have been able to become far more efficient and error is greatly reduced.
