How Do You Look Up a ZIP Code?

By Staff WriterLast Updated Oct 2, 2020 6:41:54 PM ET
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Photo Courtesy: Noam Galai/Getty Images

ZIP codes were first introduced in the United States during World War II in 1943. At the time, the postal service was looking for ways to simplify the way it did business due to so many employees having left to serve in the war effort. The postal service needed simplification since so many employees left to serve. The Zone Improvement Plan (ZIP), as it was known, made it easier to identify where a letter needed to go, which in turn simplified the delivery process for postal employees.

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Initially, the Zone Improvement Plan used two-digit numbers. The first denoted a major city — smaller cities and towns were only added later — while the second denoted the state that city was in. As the number of people and cities grew, more numbers were added. Today, the first digit represents a large area. For instance, zero stands for the Northeast, while nine represents much of the west. The second and third digits signify a regional central post office, while the fourth and fifth digits represent a smaller postal zone

One example offered by BusinessInsider is the ZIP code 10014. The first number tells you that the address is in either Delaware, Pennsylvania or New York. The two zeros mean that the regional post office is New York Sectional Center. Finally, the 14 places the letter’s destination in Manhattan’s West Village. Not bad for five seemingly random numbers.

What Is a ZIP Code?

ZIP codes were first introduced in the United States during World War II in 1943. At the time, the postal service was looking for ways to simplify the way it did business due to so many employees having left to serve in the war effort. The postal service needed simplification since so many employees left to serve. The Zone Improvement Plan (ZIP), as it was known, made it easier to identify where a letter needed to go, which in turn simplified the delivery process for postal employees.

Gettyimages 1271246661 1
Photo Courtesy: Noam Galai/Getty Images

Initially, the Zone Improvement Plan used two-digit numbers. The first denoted a major city — smaller cities and towns were only added later — while the second denoted the state that city was in. As the number of people and cities grew, more numbers were added. Today, the first digit represents a large area. For instance, zero stands for the Northeast, while nine represents much of the west. The second and third digits signify a regional central post office, while the fourth and fifth digits represent a smaller postal zone

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One example offered by Business Insider is the ZIP code 10014. The first number tells you that the address is in either Delaware, Pennsylvania or New York. The two zeros mean that the regional post office is New York Sectional Center. Finally, the 14 places the letter’s destination in Manhattan’s West Village. Not bad for five seemingly random numbers.

Looking Up Zip Codes

Once upon a time, your choices for looking up a ZIP code were pretty much to hope it was in your phone book or ask someone who lived near the recipient and pray that they shared an area code. With the internet, however, finding ZIP codes is easy.

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Photo Courtesy: Joe Sohm/Visions of America

You can use a tool on the U.S. Postal Service’s website to look up the area code of either a specific address or a particular city. Similarly, you can enter in an unknown ZIP code and find out the city it corresponds to. (Just be aware that many cities have multiple ZIP codes).

There are many other online tools, such as those at Zip-Codes.com and UnitedStatesZipCodes.org, that serve a similar function. However, looking up a ZIP code doesn’t even have to be as complicated as that. A simple search on Google or other large search engine is likely to reveal the location tied to a ZIP code and vice versa. In fact, this even holds true with telephone area codes.

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The Last Four Digits in a ZIP Code

You’ve probably ZIP codes with an extra four numbers at the end, but it may not be clear what they actually do — after all, mail seems to get where it needs to go regardless of whether or not those numbers are there. While it’s true that they’re not essential, they do serve a purpose.

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Photo Courtesy: Robert Alexander/Getty Images

These numbers represent something even more specific: the particular delivery route to the destination, as well as around 20 or so homes, businesses or other locations. By including those extra four digits, you help the U.S. Postal Service sort the mail more efficiently and speed up the delivery of your letter or package. If you’re in a particular hurry for your mail to arrive at its destination, you can find the latter part of a ZIP code using the tool on the U.S. Postal Service’s website above (as well as many similar sites) so long as you know the address of the location you’re looking for.

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When you use the USPS look-up tool at Tools.USPS.com, you'll also get the ZIP + 4 code along with the five-digit code. If you are typing in a general street name, you'll receive all the ranges of ZIP + 4 codes along the street or area.