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Organizing America

A History of the ZIP Code

In 1962, Elvis Presley had a hit song “Return to Sender,” which he performed in the film Girls! Girls! Girls! The song is about a man mailing a letter to his girlfriend after an argument. She keeps writing on the letter “Return to sender.” In one of the verses of the song, Elvis sings “…no such number, no such zone.” (Presley). The phrase “…no such zone” refers to the one of the most important inventions the United States Postal Service has ever offered to the American people, the “Zoning Improvement Plan” coding system, or the ZIP Code™.

Begun as a way to improve the overall efficiency of the United States Post Office’s mail sorting and delivery system in 1963, the ZIP Code zone system has been in place for over 50 years in the United States now. We may not even think about those numbers we write out every time we address a letter or pay a bill. The ZIP Code has taken on a life of its own, acquiring independent value that extends beyond its role in facilitating postal delivery services. Its contribution to America’s soft infrastructure is as important as the postal service’s contribution to the development of highway, railroad, and air infrastructures. Furthermore, despite declining mail volumes, use of the ZIP Code by individuals and businesses has expanded over the years, from a way to more efficiently sort and deliver mail to having significant impact on the soft infrastructure of the U.S. economy.

The Postal Department

In Colonial America, postal services were very limited until almost the end of the 17th century. Each colony received mail from England, and there was a monthly service between Boston and New York City and a weekly service between Philadelphia and New Castle, DE. In 1692, the English Crown created the Office of Postmaster General for America under a patent granted to Thomas Neale. Under this patent, he was guaranteed a monopoly over postal communications for 21 years. However, operating expenditures for the fledgling Postmaster were considerably greater than the revenues he took in, and Neale died heavily in debt in 1699 (Sorkin).

Postmaster Benjamin Franklin Benjamin Franklin was postmaster general in Philadelphia as well as deputy postmaster of North America

Benjamin Franklin became postmaster general in Philadelphia in 1737 and, subsequently, deputy postmaster of North America. He quickly instituted several improvements, such as an additional number of relatively short routes, milestones on major roads, and night delivery. In 1755, he established a packet line between New England and New York City, and later between Falmouth, MA, and Charleston, SC. A letter that took three days from Philadelphia to New York City in 1720 often took only one day by 1754 (ibid).

Franklin was adamant that the users of the mail should shoulder the cost of the service, and it should not rely on government subsidies in order to operate. In the 18th century, the sender of the mail paid for its delivery to a central point in a distant city. Home or business delivery was rare and, when available, incurred an extra charge. The prevailing philosophy regarding the financing of the system was that it should be a source of federal revenue but not a burden on the colonial government.

In 1782, after the American Revolutionary War, “An Ordinance for Regulating the Post Office of the U.S. of America” established that the “United States in Congress assembled is by the Articles of Confederation vested with the sole and exclusive right and power of establishing and regulating post offices throughout all the United States…” (ibid). The U.S. Constitution contains only brief mention of the postal service in Article I, Section 8, which reads, “The Legislature of the United States shall have the power…to establish postal offices and post roads.” It is highly likely that the Founding Fathers intended that the post office should monopolize the postal service of the United States. There was almost no discussion of the post office in the state constitutional conventions. Alexander Hamilton made one reference to the post office in Federalist Paper No. 68 concerning the establishment of post offices and post roads:

The power of establishing posts roads must, in every view, be harmless power, and may perhaps, by judicious management become productive of great public convenience. Nothing which tends to facilitate the intercourse between states can be deemed unworthy of the public care (Rossiter).

After the ratification and passage of the Constitution, legislation enacted since the time of the Continental Congress consistently protected the government’s postal monopoly. An act in 1792 made illegal the establishment of a private postal service, “whereby the general Post Office may be injured” (Sorkin). In the Postal Act of 1827, individuals convicted of illegally competing with the postal service were made subject to criminal penalties. However, illegal carriers obtained roughly two-thirds of the federal business between 1840 and 1844. The Postal Act of 1845 prohibited private firms from making express deliveries, and this was the last important general postal legislation act until the Postal Reorganization Act of 1970 (ibid).

Before the 1870s, most Americans did not exchange mail or organize their daily lives around the expectation of mail. During the early decades of the U.S. Post Office, mail was slow, and systems of collection and retrieval were irregular (Henkin). One of the primary reasons for the financial difficulties of the Post Office in the 1840s was the high letter rates. Americans simply could not afford to correspond via mail due to its cost. For example, it cost 18.5 cents to send a letter from New York City to Troy, NY, in the 1840s, but it only cost 12.5 cents to send a barrel of flour the same distance (Sorkin). Therefore, many Americans opted to avoid using the post office and send their letters via friends or relatives or a private postal service.

By the end of the Civil War, however, westward expansion was in full swing; merchants were thriving; and the Post Office Department instituted a flat-rate postage system as well as introducing stamps, envelopes, registered letters, and money orders. In addition, the Post Office Department had established city-free delivery. In 1863, the Post Office Department first grouped mail into various classes with letters comprising first class; periodicals, magazines, pamphlets, and even book-length manuscripts mailed between author and publisher were all designated second-class mail. Other printed mail was placed in third class and charged a higher rate to post (ibid). The bones of the current U.S. Postal Service were in place.

The Advent of the ZIP Code

Currently, the U.S. Postal Service delivers 40% of the world’s mail to 5% of the world’s population, a task made more daunting by the size of the United States (U.S. Postal Service). The Post Office Department’s original mail sorting methods depended solely on local addresses and hand sorting. With continuing western expansion and a booming population, especially in the years following World Wars I and II, the average mailed letter was handled by 8 to 10 employees before it made its way to its recipient. Manual sorting became even more laborious as customers’ use of the mail grew by almost 160% from 1940 to 1965 (ibid).

Forward-thinking postmaster generals imagined following the industrialization and standardization of industries such as the automobile and automating the mail’s sorting and handling processes to handle the increased workload faced by the postal service employees. In 1961, the post office established the Nationwide Improved Mail Service (NIMS) program, which standardized the physical dimensions of the mail through the establishment of envelope sizes and shape limitations (ibid). Then, they needed to establish a machine-readable code to expedite the sorting of the mail on a national level.

To develop this code, the Post Office Department turned to a sorting system it had started using in a limited capacity in 1943. This system divided up large cities into 2-digit postal zones which were written by mailers in the lower line of addresses, called local zone numbers. These 2-digit codes made mail sorting more efficient, but it was limited to large cities, was not a mailing requirement, and was used primarily by large mailers (ibid).

Philadelphia Postal Inspector Robert Moon saw the value of coding the postal system, and in 1944, he submitted a proposal to create a national 3-digit code system to assign the country to various processing hub centers. He strongly believed that a national coding system was “necessary to keep up with the mail volume after World War II” (ibid).

Postmaster General Day In 1944, Philadelphia Postal Inspector Robert Moon submitted a proposal to Postmaster General Edward Day to create the first national 3-digit ZIP Code™ system

After persistent submissions, Robert Moon finally was able to pitch his idea to Postmaster General Edward Day, who was intrigued by Moon’s concept and combined it with the 2-digit local zone numbers to create the 5-digit ZIP Code, which is the basis of the ZIP Code used today


Americans were skeptical of the new ZIP Code. The United States Postal Department responded with a brilliant advertising campaign, a media blitz, led by a soon-to-be popular cartoon character, Mr. Zip, in order to win over the hearts and minds of the American people to the benefits of the new ZIP Code zone system. Originally called Mr. P.O. Zone, Mr. Zip was designed in the 1950s by Howard Wilcox for the Cunningham and Walsh Advertising Agency (Curtin).

Mr. Zip’s original purpose was to advertise a bank-by-mail campaign for the Chase Manhattan Bank in New York City. The Post Office Department acquired the rights to Mr. P.O. Zone from American Telephone & Telegraph Company AT&T and made a few changes to him, including elongating his body and at times giving him a letter to hold in his hand (ibid). They also changed his name to Mr. Zip. He symbolized the speedy delivery of the mail that the post office hoped to achieve by implementing the new ZIP Code, and he was meant to excite all of America as well. The Post Office Department hoped that friendly Mr. ZIP would win over reticent Americans.

ZIP Code History Cheerful cartoon character Mr. Zip was officially introduced in October 1962 to promote the new Zip Code™ nationally

Mr. Zip was officially introduced to the postmasters in October 1962 at the same convention when the ZIP Code was introduced. Each postmaster was photographed hugging Mr. Zip, and the photos were used on the name tags for the duration of the convention. Also that October, the Washington Post and the Times Herald briefly mentioned Mr. Zip and the message he was promoting to mailers across the United States. Newsweek magazine in its December 10, 1962, issue had a short article entitled “Aunt Minnie’s Tip…Look for Mr. Zip” (ibid). Although these articles were published before the actual launch of the Zip Code, they foreshadowed the hype and public attention and they did much to spread greater awareness of the ZIP Code campaign.

With Mr. Zip at its side, the Post Office Department formally launched its nationwide campaign to promote the use of the ZIP Code on July 1, 1963. It featured illustrations of Mr. Zip in the promotional materials made available to local post offices to educate and encourage customers to use the ZIP Code. Mr. Zip also began making promotional appearances around the country. His likeness appeared everywhere, from local post offices to the sides of mail delivery vehicles. The post office saturated the country with Mr. Zip’s image―even postal workers had to wear Mr. Zip pins! This Mr. Zip blitz made him into a household name and called early attention to the new ZIP Code system. And while he never appeared on his own stamp, Mr. Zip’s likeness graced the margins of most of the other stamps sold by the post office at the time. The Postal Department did not want Mr. Zip in the Comics section of the newspapers, though; it wanted Mr. Zip integrated as much as possible into “social events and the very fabric of town life” (ibid).

Around the mid-1960s, the post office held a series of experimental promotions called “ZIP Code Week” in a dozen cities, and the success of these experiments led to a National ZIP Code Week, which was an intensive educational campaign focusing on large cities with multiple ZIP Code zones (ibid). The original ZIP Code Week took place from October 10–15, 1966, and 302 cities across the U.S. participated (ibid). This week also served as an important reminder that as of January 1, 1967, homes and business would be required to use the ZIP Code in their mailing addresses. Mr. Zip was easily incorporated into ZIP Code Week festivities.

ZIP Code Success

ZIP Code Regions The ZIP Code™ was formally introduced in 1963 and opened the way for fundamental changes in U.S. postal service operations

With its formal introduction in 1963 and successful implementation, the ZIP Code opened the way for fundamental changes in the conduct of basic postal operations. Before the ZIP Code was established, local post offices exchanged mail with each other. The ZIP Code system divided the United States into 10 large, geographic areas, assigning to each a number from 0 to 9 to become the first digit of a 5-digit ZIP Code number. Key post offices in each area were designated sectional centers, and each of these was assigned two numbers, which made up the second and third number in each code. Finally, local post offices within each center’s area were designated by the last two digits (Tierney).

The advent of the ZIP Code and the establishment of sectional centers made certain changes possible in processing and delivering mail. First, with the 5-digit ZIP Codes designating specific destinations around the nation, postal clerks could sort mail by numbers and no longer had to memorize the previously required sorting schemes. Second, the ZIP Code system made it possible to develop sorting machines. And third, a central postal facility—the sectional center—could be designated to process most of outgoing mail for all post offices in a given area, which greatly expedited sorting and delivery of the mail. By the time the Postal Department was reorganized and renamed the United States Postal Service in 1971, these fundamental changes could be made.

The Postal Service fought hard for their new system and won because it had fought so hard for the public’s support―and eventually the American people did come around to supporting the ZIP Code zone system. In 1970, 84% of the large business mailers agreed that the ZIP Code was a good idea (ibid). As compliance with the ZIP Code neared 100% in the 1970s, the newly renamed United States Postal Service cut back on its marketing campaign, and Mr. Zip’s image disappeared from the margins of postage stamps. In 1983, with the introduction of the new ZIP+4 zoning system, Mr. ZIP was retired from the USPS. And they simply did not see the need to launch a similar promotional campaign to promote ZIP+4.


In 1983, the USPS expanded the number of digits in the ZIP Code to nine and called it ZIP+4. These additional digits were meant to identify a street or office building. The Government Accounting Office (GAO) concluded in 1983 that this 4-digit expansion coupled with new automation equipment would save the USPS and external mailers a total of $5.26 billion over the next 16 years (ibid). Robert Mitchell, principal economist for the USPS, stated, “when we introduced ZIP+4 back in the late seventies we had a horrible national reaction. Everybody talked about George Orwell’s 1984, and Congress got all excited. People felt very strongly about this business turning American into numbers” (ibid). The USPS ultimately compromised with a nine-digit system in which the first five digits remained the same.


Today, the nine-digit Zip Code has been expanded to 11 digits, which allow ordering by carrier-walking sequence (ibid). Customers still only need to supply the five-digit ZIP Code to the USPS for mailing, but the additional digits increase accuracy and provide better service. While the ZIP+4 represented a side street, building, or block face location of an address, the additional digits are the last two numbers of a street address. By late fall 1990, the postal service began giving discounts to business customers who sent their mail with the new 11-digit Zip Codes (Hovey). While the ZIP+6, or the Advanced Bar Code System, was not instituted until 1993, the USPS sought to reward its customers who started the habit early.

Even the critics of ZIP+6, who feel that the additional two digits are overkill and unnecessary, have to agree that ultimately, writing the two additional numbers at the end of the address is business as normal (ibid).

Geocoding and the Future?

GPS Satellite Navigation Geocodes, which pinpoint individual locations more accurately than the ZIP Code™, could represent the future of a global mailing system

While Americans have transitioned mostly smoothly once more to the 11-digit ZIP Code, the next step could be to use geocodes, and this solution could be truly universal. A geocode is any number or code that relates to a physical location. Existing postal codes and ZIP Codes are a form of geocode, although most existing kinds would not have enough delivery points because they are designed for only single-country mail systems (Cartledge). The concept of geocoding has exploded in recent years as tools such as Google Maps and GPS satellite navigation software are becoming everyday tools.

Although the current address system and ZIP Code zone system are very advanced in the United States, geocoding could represent the next step, by enhancing these systems. Already, the Postal Service has created a same-day delivery pilot called MetroPost. This pilot program―similar to Amazon, Google, and Wal-Mart delivery models―is already being used in the San Francisco area. MetroPost utilizes the ZIP Code first to set the boundaries of what delivery points are eligible for same-day service. Then each address that has a package to be delivered is geocoded so that an optimized point-to-point route can be set (U.S. Postal Service).

Geocoding could also lead to a standardized international mailing system. A standard international geocode system would help in delivering goods to countries that don’t use Western alphabets and to people who are mobile. Xinhang Shen, founder and president of the Canada-based company NAC Geographic Products, uses the example of the Mongolians. Shen’s company first devised its system in 1995, and the NAC code system uses letters as well as numbers in order to keep codes shorter and, therefore, hopefully more socially acceptable. Shen stated: “In Mongolia, a lot of people live in yurts that move around. You can’t have an address, but if you tell the postal service the geocode where you are located, they can deliver” (Cartledge). So far, only Somalia, in 2003, and Mongolia have adopted the NAC’s geocoding system.

Besides working with countries, Shen’s company is also working with mail services giant Pitney Bowes on linking its mailing software with NAC’s geocoding system, and they have already discussed setting up a universal geocode system to improve mail sorting. Shen is also believed to be an inspiration behind the Dublin-based Go Code geocoding system, which is also based on longitude and latitude and uses seven-digit combinations of letters and numbers that resemble British or Canadian postal codes and provides accuracy up to five square meters (ibid). Go Code is currently in negotiations with the Irish government to use this geocoding system at a national level.


David M. Henkin writes: “We still rely on the U.S. Postal Service for much of our daily business and many of our daily pleasures. Even in an age of digital information, the postal system remains a central and almost wondrous institution.” For a small fee, an elaborate national bureaucracy comes to our home and delivers items of our choosing virtually anywhere in the world. The ZIP Code zone system, introduced in 1963, revolutionized the way the United States Postal Service does business, has had an enormous impact on American national infrastructure, and has even influenced American soft infrastructure. The advent of the ZIP Code revolutionized how Americans send and receive mail and prepared the country for the automation and reorganization of the U.S. Postal Service so that it could adapt to meet the needs of its customers even today. But the ZIP Code is not done evolving.

The ZIP Code has become a part of the American identity. Every time a consumer fills out a warranty card accompanying a new camera or refrigerator or subscribes to a magazine, another piece of information drops into a computer running software structured by an 11-digit ZIP Code. If in the future, the U.S. Postal Services decides to apply GIS technology, the ZIP Code could reach out until it covers every American, no matter where they live, and we could be looking at a future where everyone on the planet, no matter how remotely they live, could have access to a universal mail service.

-- Posted July 25, 2014


 Clinton Rossiter, ed. 2003. The Federalist Papers. New York, NY: Signet Press.

 Cartledge, James. “Addressing the World: How Geocodes Could Help Billions Start Using the Mail.” Post & Parcel. November 9, 2011. Accessed May 2, 2014.

 Curtin, Abby. “Flashing across the Country: Mr. Zip and the ZIP Code Promotional Campaign.” Smithsonian National Postal Museum. Accessed May 2, 2014.

 Henkin, David M. 2006. The Postal Age: The Emergence of Modern Communications in Nineteenth-Century America. Chicago, IL: University of Chicago Press.

 Hyman, Louis. 2011. Debtor Nation: The History of America in Red Ink. Princeton, NJ: Princeton University Press.

 Presley, Elvis. “Return to Sender.” SongLyrics. Accessed May 15, 2014.

 Sorkin, Alan L. 1980. The Economics of the Postal System Alternatives and Reform. Lexington, MA: Lexington Books, DC Heath & Co.

 Stilgoe, John R. 1998. Outside Lies Magic: Regaining History and Awareness in Everyday Places. New York, NY: Walker and Co.

 Tierney, John. 1988. The U.S. Postal Service: Status and Prospects of a Public Enterprise. Dover, MA: Auburn House Publishing Company.

 U.S. Postal Service Office of Inspector General. “The Untold Story of the ZIP Code.” (Report No. RARC-WP-13-006) April 1, 2013. Accessed May 2, 2014.