In the 1960’s the United States Postal Service USPS experienced a high increase in business related mail. Because of this change, the way mail was delivered had to change. Two years later, the Advisory Board of the Post Office Department made a recommendation to create a coding system that would help relieve several streamlining problems. This would later be known as the ZIP code (a.k.a. Zone Improvement Plan code).
Many years passed by as attempts to make a coding system had been tried and rejected. Finally, by July 1963, every region of the country had been assigned to a unique ZIP code. The ZIP code, however, was not made mandatory until 1967 where those of second- and third-class bulk mail were asked to use them.
In 1983, the standard 5-digit ZIP code expanded to the ZIP+4 code. This enabled the USPS to narrow their ZIP code region to a more specific region. ZIP+4 is used primarily by business mailers who prepare their mail with typewritten, machine-printed, or computerized formats so that the USPS’s scanners can read them during processing. Though it is not required to have the 4-digit add-on, it helps the Postal Service direct mail more efficiently and accurately because it reduces human error and misdelivery.
The first three digits of a ZIP code refer to a sectional center or a large city. The last two digits refer to a specific post office facility or delivery area. In ZIP+4 format, a hyphen is required to separate the first five and last four of a ZIP code. The first two of the +4 code refer to a sector or a few blocks. The last two of a +4 code refer to a specific segment or one side of a street.
ZIP codes are used by businesses all throughout the world to hone in on detailed and important information about their customers.
ZIPCODE DATA SINCE 2002