State Abbreviations and Postal Codes 2025

A Brief History on State Abbreviations and Postal Codes

If you are like most people, the chances are good that nowadays, you hardly ever write an address on an envelope and put it in the mail. However, do you get a thrill from receiving an envelope or package addressed to you? But, do you ever send off packages to other people? Even if you don’t regularly send snail mail, you are probably so familiar with the whole system of state abbreviations and postal codes that you don’t even think about it.

But the system didn’t just conveniently fall from the sky one day. It was designed with a specific goal in mind – facilitating the sending of mail as the country was expanding westward in the 1800s. We still use the same system today, albeit supplemented with the use of email and other electronic communication.

The United States had a postal service from before its founding in 1776, but as it expanded westward, the need for a more centralized, more systematic service became apparent. In 1831, The United States Postal Service (USPS) issued a directory called the Table of Post Offices. It had a listing of every post office in the country so that people could know where to go to drop off their mail and pick something up.

The Table of Post Offices encouraged people to spell out the entire name of the state, but who has time to do that? People commonly wrote out abbreviations for the states, but without a standard system in place, it would be too easy to confuse, say, Miss for Mississippi and Miss for Missouri. The Table gave a list of accepted abbreviations to prevent this confusion. As the number of states grew, so did the list of abbreviations.

In 1831, at the time that the Table of Post Offices was published, Abraham Lincoln was the postmaster in New Salem, Illinois. If someone failed to collect his or her mail, he would deliver it personally. As president, Lincoln expanded the postal service during the Civil War to include personal mail delivery to people’s homes. Nowadays, we can’t imagine a postal service that doesn’t deliver mail directly to our homes!

The Beginning of ZIP Codes and State Codes

When the United States entered World War II, thousands of postal employees left their jobs to join the military. New employees – mostly women, who were working on the home front while men were serving in Europe and the Pacific – had to be quickly trained to ensure that mail could continue to be delivered, especially letters from soldiers overseas.

The US Postal Service came up with a system known as Zoning Improvement Plan codes, or ZIP codes. The system consisted of numbers for zones in each major city so that the mail could be more quickly sorted by people who did not have extensive knowledge of the postal service. For example, Birmingham, Alabama was divided into several different zones, and an addressed envelope might say Birmingham 7, Alabama, to indicate the zone in which the address was.

The system was so helpful that it continued after the war ended in 1945. In 1963, the US Postal Service officially adopted the use of five-digit ZIP codes for every piece of mail. Today, there is roughly one post office for each ZIP code, so you probably have a post office nearby. Some places, like Manhattan in New York City, have such dense populations that one ZIP code may consist of only one or two city blocks. Other areas, like rural regions of Alaska, are so sparsely populated that one ZIP code may cover hundreds of miles.

Whereas USPS had previously requested that people write out the full name of the state, it now wanted the two-letter codes to leave room on the envelope for the ZIP code. Up until this point, the state abbreviations were usually more than two letters, such as Miss for Mississippi and W.Va. for West Virginia. The 1963 changes standardized the two-letter abbreviations into codes, so Miss is now MS. Make sure that you use the standard codes, or else you might confuse AL (Alabama) with AK (Alaska)! Today, some places have nine-digit ZIP codes to help the postal worker more easily identify the location.

There have been some modifications to the system, such as changing Nebraska from NB to NE because it was getting confused with New Brunswick, Canada. There are several US territories and associates, such as the Marshall Islands in the Pacific and Puerto Rico, which also have official abbreviations for use by the postal service. For the most part, though, the system that evolved in the early 1800s is the same system that we use today. So next time you see a package addressed to you, remember that you are experiencing nearly 200 years of American history.