This is what your ZIP code really means

Busiest Day for U.S. Postal Service
Getty Images | William Thomas Cain

When you think about it, being able to send a physical card, letter or document across the country for less than a couple of quarters is pretty cool. Consider the logistics of transporting millions of envelopes and parcels in just a matter of days. We take it for granted, but it’s truly mind-boggling.

The United States Postal Service processes and delivers 506.4 million pieces of mail every day, distributing 40 percent of the world’s mail to five percent of the world’s population. So much of this hinges on those five-digit numbers at the end of the delivery addresses.

Your ZIP code is such a minuscule piece of your life and yet it can help pinpoint the place you call home or your business location. Have you ever wondered how those numbers can provide a postal carrier–and others–information about your address?

mail photo
Getty Images | Win McNamee

Before ZIP Codes Existed

Colonists sent mail to family in England as far back as the 1600s. By the 1800s, mail was delivered via stagecoaches, steamboats and wagon trains. The Post Office delivered mail to settlements, military forts and, in more established locales, specific addresses.

When thousands of postal employees left to serve in the military during World War II, the Post Office Department began using one or two digits between the city and state for 124 of the largest U.S. cities to make it easier for less experienced workers to sort the mail.

What the Digits Mean

Philadelphia Postal Inspector Robert Moon proposed a national three-digit code system in 1944. Each code would correspond with various processing hub centers. Although he persisted, his submissions were largely ignored. However, nearly two decades later, Postmaster General Edward Day found the idea intriguing.

He combined the three digits with the existing two-digit local zone numbers already in use. The first digit is the postal area. These are typically lower in the east (Maine starts with 0) and higher in the west (California begins with 9)  The next two digits delineate the Sectional Center Facility, which is a processing and distribution center. The last two numbers define the local zone.

Implementing The Zone Improvement Plan (ZIP)

The Post Office announced the nationwide five-digit ZIP Code at a postmasters’ convention in October 1962. There were concerns that people might be hesitant to use the numbers, as consumers had been reluctant to begin using area codes when they were introduced several years earlier.

A “saturation campaign,” complete with a cartoon character named Mr. Zip, helped residents from schoolchildren to adults learn about and begin using the five-digit numbers when mailing correspondence or packages. The USPS reports achieving nearly 100 percent ZIP Code compliance before Mr. ZIP was retired in 1983.

Wikimedia Commons | Brianga

What’s With The +4?

That same year, the United States Postal Service a new “ZIP + 4” zoning system. The extra four digits were added to streamline mail sorting, allowing machines to identify a specific carrier route and block. This addition eliminated the need for manual letter sorters and decreased the need for more postal workers. While the ZIP + 4 system is used today, it is primarily utilized by large volume mailers.

Interesting ZIP Codes

You probably know that the ZIP code for Beverly Hills, California is 90210. However, with nearly 42,000 ZIP Codes in the country, many others have interesting features, such as the following.

  • 00501 is used for the Internal Revenue Service in Holtsville, NY and is the lowest ZIP code numerically.
  • The highest is 99950, which is the ZIP code for Ketchikan, AK.
  • 12345 is a unique ZIP code for General Electric in Schenectady, NY.
  • Smokey Bear has his very own ZIP code: 20252.

[h/t Reader’s Digest]


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About the Author
Tricia Goss
Tricia Goss is a Texas-based writer and editor with nearly two decades of experience. She is passionate about helping readers improve their skills, gain knowledge and attain more happiness in life. When she’s not working, Tricia enjoys traveling with her husband and their dog, especially to visit their five grandchildren.

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