Zip Code Or Postal Code

All You Should Know About Zip Code – What is Zip Code, How Does Postal Code Work, Who Uses Zip Code & More

The term ZIP is an acronym for Zone Improvement Plan; it is believed that mail travels faster and more efficiently when the sender uses the code in the postal address.

The term ZIP code was originally registered as a servicemark by the USPS (United States postal service); its registration expired in 1997. The early history and context of postal codes began with postal district/zone numbers.

A  ZIP code is a postal code used by the United States postal service. It was launched and initiated in 1963, the basic format consisted of five digits.

By the early 1960s, a more coordinated and organized system was needed, and non-mandatory five-digit ZIP Codes were introduced nationwide on July 1, 1963.

In 1983, an extended ZIP+4 code often called “plus-four codes”, “add-on codes”, or “add-ons” was introduced; it included the five digits of the Postal code, followed by a hyphen and four digits that designated a more specific location.

A ZIP+4 code uses the basic five-digit code plus four additional digits to pinpoint a geographic segment within the five-digit delivery area, such as a city block, a post office box, or any unit that could need an extra identifier to help in mail sorting and delivery.

However, the new format was not accepted generally by the public; it ultimately became out-of-date with modern technology. In general, the mail is read by a multiline optical character reader that almost immediately determines the appropriate ZIP+4 code from the address.

The add-on code is often the last four digits of the box number, that is, PO Box 102040, Batavia, NY 14021-2040), zero plus the last three digits of the box number (e.g., PO Box 17727, Eagle River, AK 99577-0727), or, if the box number consists of fewer than four digits, enough zeros are attached to the front of the box number to construct a four-digit number (e.g., PO Box 77, Juneau, AK 99750-0077).

For post office boxes, the universal (but not constant) rule is that each box has its very own ZIP+4 Code, so it must be looked up one by one for each box (e.g. using the USPS’s official ZIP code lookup tool, and being sure to enter just city and state, not the 5-digit ZIP).

Postal Bar Code

The ZIP Code is frequently translated into an Intelligent Mail barcode that is shown on the mail piece to make it easier for automated machines to sort.

A bar code can be printed by the sender but this is not recommended as the address-to-ZIP lookup tables can be considerably out of date.

In general, the post office makes use of optical character recognition technology, though in some cases an individual might have to read and enter the address.

Customers who send bulk mail can get a discount on the postage if they have printed the barcode themselves and have sorted the mail before.

A mailing list must be regulated with an up-to-date Coding Accuracy Support System (CASS)-verified software that adds and authenticates a full, correct ZIP+4 Code and an additional two digits representing the exact delivery point.

Furthermore, mail must be sorted in a specific manner to an 11-digit code with at least 150 mail pieces for each qualifying ZIP Code and must be accompanied by documentation confirming this.

The assigning of delivery point digits (that is, the 10th and 11th digits) is meant to ensure that every single mailable point in the country has its 12-digit number.

The delivery point digits are calculated based on the primary or secondary number of the address.

All You Should Know About Zip Code

Types And Uses Of Zip Codes

There are majorly four types of Postal code / ZIP code, which are:

  • Unique: This is assigned to a single high-volume address.
  • Post office Box-only: this is used only for PO Boxes at a given facility, not for any other type of delivery.
  • Military: It is use to route mail for the military.
  • Standard: this contains all other ZIP Codes.

Unique ZIP Codes are used for governmental agencies, businesses, universities, or buildings that receive very high volumes of mail that warrant them to have their ZIP codes.

In areas surrounding a certain post office, home, and maybe business mail delivery address uses a particular ZIP code, which is then known to be a Standard ZIP Code.

Zipcodes are very essential and significant in top world countries like the United States, Canada, the United Kingdom, and almost every country in the world.

ZIP code is very important in sending mails, delivery, and logistics fraud detection and research demographic dissolution. Below are some major uses of  Zip code / postal code:

  • Mail services: this is the main use of zip codes and postal codes.
  • Delivery services: This is used for the internal routing of a package.
  • Statistics: For example, in the United State, there are over 42000 zip codes. Apart from delivery mails, zip codes are also used in gathering statistics.
  • Marketing (Zip-codes marketing).
  • Legislative districts.
  • Internet purposes: You will often find zip codes under most education or e-Commerce website registration page.

The use of ZIP Codes for applications other than postal delivery can present many challenges and there are several major issues worth noting. It is not unusual for postal delivery routes to be readjusted or ZIP codes to be split.

Significantly, ZIP Codes can be discontinued, added, or expanded within months or years. Thus, when there is a slight modification in ZIP Codes and their geographical coverage, it can cause a multi-scale discontinuity.

Another difficulty associated with ZIP code areas is the significant variation in geographic extent.

The USPS does attempt to optimize the size or population allocation of ZIP codes given that the sole purpose of the ZIP code is to expedite the delivery of mail. As a result, ZIP codes can range in size from a single building to a delivery zone spanning hundreds of square miles.

What Is The Difference Between Zip Code And Postal Code?

People usually tend to misplace and get confused about these words, but the truth is that they serve the same purpose. The major difference is that zip code is mainly used in the US, while postcode or postal codes are used in other countries.


In this article, I have given a clear and comprehensive review of everything you need to know about ZIP Codes and postal codes, the types of ZIP Codes, and also the uses of ZIP Codes.

You have every important detail on ZIP Codes discussed in this article and now know the importance and use of your zip or postal code.

Thank you for reading and I hope this article is of help to you.

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