What is a Zip Or Postal Code?

Whether you are moving into a new house, buying a business premises or setting up an office space it is a good idea to understand what exactly is a zip or postal code. Basically, they are unique nine-digit codes that are assigned to locations by the Postal Service to simplify and speed up delivery of mail. In some cases, these codes are based on geographical areas or administrative boundaries.

The first three digits of the zip code signify the zone or region, the second two digits identify the specific city in the area and the last four digits signify the postal delivery unit. The ZIP code system was introduced in 1963, after a proposal by Robert Moon, a Philadelphia postal inspector, to simplify the country’s address structure.

When the ZIP code was introduced in the US, people were initially skeptical and reluctant to change their preferred place names. However, the system was eventually accepted as it improved mail delivery times and aided the postal service to accurately measure population growth between censuses.

In 1983, the five-digit system was expanded to include an additional four digits. The new system, which is sometimes referred to as the ZIP+4 or add-on codes, allows senders to indicate a more precise geographic segment within the five-digit delivery area. This is useful for large businesses, apartment complexes and other high-volume recipients of mail who can benefit from an even more accurate level of postal addressing.

However, in some cases the use of zip codes has resulted in confusion. For example, a town in California named Signal Hill is not listed in the official city records and its residents have petitioned the Postal Service to change its ZIP Code to that of nearby Long Beach. The confusion can have financial consequences, as communities that are listed incorrectly may receive fewer funds from the state based on census estimates.