Two Letters, Twenty-Three Characters

CA. TX. NY. FL. American state codes are so familiar they feel like part of the map, as if each state was born with its two letters.

They’re barely sixty years old.

For most of American history, states were abbreviated however you liked. Calif. or Cal. Penn. or Penna. Mass., Miss., Minn., Mich. The Post Office had recognised common abbreviations as early as 1831, but it would really rather you spelled the name out in full. It didn’t have much confidence in Mich. and Miss.

Then, in July 1963, the Post Office launched the ZIP code. It was a five-digit number meant to make mail sortable by machine. Three months later it had a problem. Its addressing equipment could handle a line of no more than 23 characters for the city, the state and the ZIP code together. Try fitting “Massachusetts” plus a town name plus five digits into 23 characters.

So in October 1963, the Post Office published a list of two-letter codes for every state. Nobody designed it for clarity or branding. It was a fix for a space problem. A clerical limit on line length became one of the most recognisable naming systems in the world.

It wasn’t perfect first time. Nebraska was originally NB. In 1969 it became NE, to avoid confusion with New Brunswick in Canada. That’s the only change to a state’s code since 1963. Everything else has stayed put for six decades, printed on licence plates, embroidered on caps and argued over in quizzes. Is MI Michigan or Mississippi? (Michigan. Mississippi is MS. Missouri is MO. Good luck.)

What I love about this story is how ordinary the cause was. Nobody sat in a room deciding what each state should be called. An engineer counted the characters on a machine. And because it worked, and everyone used it, it stuck.

Most standards start like this. The width of a train track, the order of keys on a keyboard, the length of a tweet: a practical constraint becomes a convention, and the convention becomes identity. Within a generation, nobody remembers there was a choice.

That’s worth remembering when you design anything other people will use: a naming convention for files, a code for products, the abbreviations in your reports. The quick fix you invent this afternoon may well outlive you. Make it a good one.