What Is a Postal Code? A Brief History of Zip Codes

A hand holding an open envelope with a fake address to John Doe
When making an online purchase with your credit card, zip code is typically a required field. But what does that postal code even mean? peepo / Getty Images

90210. SW19. 150-6110. What do these series of characters have in common? They're all postal codes in specific areas of major cities — Los Angeles, London and Tokyo, respectively, if you were wondering.

But what is a postal code and what is its purpose? Let's dig in.

What Are Postal Codes?

Most countries use postal codes, a series of letters or numbers (or a combo of both) that point to a postal address. They ensure your package and mail delivery reach the correct destination. In the United States, they are five characters long and go by the term "zip code."

Aside from helping mail carriers, your postal code information plays a role in your online transactions. When filling out your payment information, an online shop will often ask for your credit card's billing address as an extra layer of protection against fraudulent activity.

"Some merchants may ask for zip codes as a security measure," according to Capital One. "It's part of the authorization process when you use your credit card to make a purchase. If your card is stolen and all they have is your name and credit card number, it may prevent an unauthorized purchase from taking place since they likely don't know your zip code."

Origins of the Postal Code

According to the Guinness World Record's page for the “first use of postal codes,” Sir Rowland Hill proposed the postal code system for London.

The original code divided London along 10 sections, such as WC for Western Central, N for North and S for South. The system went into effect in 1857 and helped speed up the distribution of local letters.

The Birth of Zip Codes

The United States uses zip codes, and there are currently 41,704 codes pointing to different delivery points across the country.

The zip stands for "Zone Improvement Plan," a 1963 program to enhance mail sorting and deliver mail more efficiently. It did more to identify locations; postal codes also made it easier to establish mailing routes.

The U.S. Postal Service started using zip codes on July 1, 1963. This new system cut down on the amount of sorting — mail previously went through about 17 stops — for post offices. Zip codes replaced an older system that eventually became too cumbersome as the need for more postal zones increased.

Deciphering U.S. Zip Codes

The five digits each correspond to a specific area. For example, the first digit ranges from 0 to 9 and is for the general area. The number 0 is for the Northeast area, and 9 is for the West Coast, Hawaii and Alaska. The two numbers that follow are for the regional area and the last two numbers are for the post office or postal zone.

Modern-day postal codes in the United States have remained mostly the same, though some changes have taken root. For example, in 1983, there was an addition of the +4 Code, the four additional digits that follow a zip code, which made post codes even more specific and deliveries more expedient.

99701: The Jolliest Zip Code

To help bring attention to the five-digit zip code, the Post Office enlisted Santa Claus' help. It encouraged children to address letters to Santa with his new zip code: 99701.

Original article: What Is a Postal Code? A Brief History of Zip Codes

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