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What is a postal code, a zip code, and how do they differ?

Whether you’re shipping a high-value package to a customer or sending out a holiday card to a loved one, sending documents and packages from one place to another necessitates the use of valid address data in order to ensure prompt and accurate delivery. The codes required at the end of addresses—also referred to as postal codes or zip codes—play a crucial role in helping mail carriers identify geographic locations, points of delivery, and mailing routes.

But if we examine these codes further, what is a zip code, what is a postal code, and how do they differ? In this article, we’ll break down the key notes you’ll want to know.

What is a postal code?

Introduced in 1959, a postal code refers to the coding system used by various countries throughout the world to simplify the processing and distribution of mail. Whether a package is shipped within a state, across a given country, or to another country entirely across the world, these combinations of numbers (and sometimes letters) form a specific identification code that allocates delivery points to a specific location.

It’s important to note that the format and implementation of these codes will vary depending on the specific geographical location they’re tied to, so it is likely to see postal codes that differ from country-to-country. Regardless of structure, the aim of the postal code remains consistent—to ensure greater accuracy and efficiency in the exchange and delivery of mail.

What is a zip code?

Introduced in 1963, the zip code was developed by the United States Postal Service® (USPS) to denote the various individual post offices scattered across the country. The rapidly booming growth in the country meant that a new system reliant on numeric value was essential to deliver mail vs. sticking to the traditional dependance on the recall of mere cities and states.

By 1967, all mail processed and delivered throughout the US now implemented the newfound zip code system. In the United States, zip codes are at least five digits long and represent the national area, region or city, and delivery area for a given address.

Wondering how to break this key piece of information down even further? Here’s how to read a zip code:

  • The first digit: this number refers to the national area, or defined group of states.

  • The second and third digit: this set of numbers signifies a region within this group, such as a large city.

  • The fourth and fifth digit: these numbers represent the associate post office or delivery area of a region.

These five digits are required to send mail within the US. However, we’ll cover the addition of plus-four codes, which are used to ensure even greater accuracy in mail delivery, below.

ZIP+4 Codes: a look at full zip codes

Most people are familiar with the five-digit zip codes we described above. But, the growing need to enhance mail sorting and the delivery process of mail meant that additional information was required for further growth and development of this system. Cue ZIP+4 – the additional four digits that act as an added identifier at the end of zip codes.

ZIP+4 codes notify the postal carrier of a geographic segment present within a delivery area. These codes are affixed to a 5-digit USPS® Zip Code once the address has been validated and standardized, pinpointing an address down to a few block radius with maximum accuracy. Overall, these additional appended numbers serve to further increase the precision of mail delivery.

Zip code vs postal code–how do they differ?

In essence, both postal codes and zip codes serve a very similar purpose—which is appending additional information to an address to ensure fast and accurate mail delivery for users.

Zip code refers to a type of postal code and is used primarily in the United States and the Philippines. The postal code, however, is typically utilized by the rest of the countries scattered throughout the world.

Unlike postal codes, which can contain a mixture of numbers and letters, zip codes only contain a combination of numeric values. Regardless of their name or structure, most countries leverage a coding system—whether a zip code, postal code, or other structure—to ensure the rapid and efficient delivery of mail to users.

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Why zip code (and other address data) accuracy matters

With the use of zip code information, business owners can ensure that their packages reach consumers accurately while reducing the risk of damage, delays, or any further complications during the process. However, they are only able to enjoy success when zip codes—and other key address information—is accurate.

At Experian, we provide businesses just like yours with access to address verification tools that leverage fine-tuned technology to capture accurate data at the point of entry. Not convinced?

See for yourself why businesses trust us to validate over 6+ billion requests each year.

 

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