What Do the Numbers in a Zip Code Mean?

Since the United States Postal Service introduced the system of zip codes, mail has been getting delivered more quickly and more efficiently.

Here's how zip codes work. The United States and its possessions are divided up into 10 large areas. Each area has a number between 0 and 9.

Suppose, for example, the zip code on a letter you are mailing is 33142.

The first number, "3", tells the postal clerk that the letter goes to the southeastern section of the United States.

The next two numbers, "31", narrow it down to Miami, Florida.

The last two numbers, "42", pinpoint the exact local post office.

If your letter has a zip code included, it has to go through much fewer handlings and sortings, and postal workers can route your letter more directly to its destination.