July 1, 1963 saw the public introduction of a new way of processing our mail by adding five numbers to each address. These new Zoning Improvement Plan numbers, or ZIP Codes, were used to speed up mail processing. The Post Office Department was in dire need of all the help it could get in handling mail, the amount of which had doubled since the Second World War. Mail across the country was pouring into post offices faster than it could be processed and delivered.
ZIP Codes divided the nation into delivery areas based on numbers beginning in the northeast and moving west. The codes began with general areas and moved to specific post offices. Think of each 5-digit ZIP Code as a group of addresses. They might be homes or businesses, schools or apartment houses. One 5-digit number might represent 10,000 delivery points—spread out over many miles in a rural area or concentrated in a few city blocks. The first digit represents a region of the country. The next two digits stand for a central post office facility in the region. The last two digits represent a post office or zone.
Postal officials anticipated some resistance by the public to using ZIP codes. Not only did people have to remember a series of numbers assigned to their address, but also the numbers assigned to each of their correspondents. The Department began a nation-wide publicity campaign for the service, using posters, radio, and television advertisements, to enticing noted singer Ethel Merman to record a ZIP code song (sung to the tune of "Zip-a-dee-doo-dah"). (1)
Unfortunately for the Post Office Department, the 1960s were a turbulent time for Americans and numbers. It was in this decade that the full switch from alpha-numeric telephone numbers (Glenn Miller’s “PEnnsylvania 6-5000” was a shout out to the phone number for The Hotel Pennsylvania in New York City), to numbers only, with area codes added in to boot! As a result, there was more public resistance to using ZIP codes than might have been anticipated. As the editor of the Decator Herald put it, “The US postoffice department comes up with a new ZIP code before most of us know our telephone area code number.” An editor from the Los Angeles Times grumbled that the new ZIP code number was one more step towards turning people into numbers. “What with wage earners already neatly tagged with social security numbers and all-digit phones multiplying, the numbers wizards should have us pigeon-holed and responding to subliminal remote control in plenty of time to beat Orwell’s 1984 deadline.” (2)
Despite that unease, today most Americans can recite their ZIP code (as well as those of close friends and family). The later introduction of ZIP+4 was less successful with the public, but was a success for bulk mailings, allowing mail pieces to be sorted more swiftly and correctly through the US Postal Service’s massive mazes of automated equipment.
Once numbers (i.e., ZIP Codes) represented addresses, barcodes representing those numbers was the next step. Barcodes are easily read by machines all along the path of a letter or parcel. From the start, they helped mail reach its destination faster and more accurately. Today, they help generate information for senders and recipients as mail moves across the country. The USPS began using barcodes in 1982. The bars represented the five digits of the ZIP Code, and helped automate mail sorting—the machines read the stripes instead of the numbers. Over the years, the USPS has used 5, 6, 9, and now 11-digit barcodes to steadily increase the speed and accuracy of mail delivery. The extra bars include “carrier sort” level coding that sorts the mail to the order it’s delivered in. (3)
Of course, the most iconic of all symbols for the ZIP Code was Mr. Zip himself. The original design was done by Harold Wilcox, an ad man from Cunningham and Walsh. The original cartoon advertised a bank-by-mail campaign for the Chase Manhattan Bank. The design was later acquired by the American Telephone and Telegraph Company (AT&T), who then offered it to the Post Office Department. Mr. Zip was finally retired by the U.S. Postal Service in 1983, such a ubiquitous face of American postal history that it is difficult to think of him as retired.
Unlike telephone area codes that stay with our cell phones as we move from city to city, ZIP Codes mark permanent locations. For that reason, they have come a long way from helping to move mail a little faster in the mid-1960s – and have become the crux of numerous statistical, geographical, and socio-political analyses. So the next time you are asked for your ZIP code, think of how those simple little five digits have given way from speeding your mail to providing an identification system to businesses and organizations around the world. Perhaps a little Orwellian after all.
About the Author
The late Nancy A. Pope, a Smithsonian Institution curator and founding historian of the National Postal Museum, worked with the items in this collection since joining the Smithsonian Institution in 1984. In 1993 she curated the opening exhibitions for the National Postal Museum. Since then, she has curated several additional exhibitions. Nancy led the project team that built the National Postal Museum's first website in 2002. She also created the museum's earliest social media presence in 2007.