There is also another type of postal code, the ZIP + 4 code. According to unitedstateszipcodes.org, the ZIP + 4 was established in 1983 and identifies an even more specific location within a ZIP code.

“Or, if you are still not convinced, there are more than 32,000 5-digit ZIP codes in the United States; so 73,000 x 32,000 is more than 2 billion possible combinations but there are only 310 ...

After the 5-digit ZIP code gets the mail to your local post office, the "plus 4" code gets it to your neighborhood. "Do you have to write it on your letters?" asked WCCO reporter Jason DeRusha.

The idea of a five-digit ZIP Code alone wasn't enough-it would be useless without a high adoption rate. And Day had been warned: executives at AT&T noted the difficulty they had in getting the ...

Let’s break down the zip code digit by digit, starting with the 4. The first digit in the zip code is a regional number. These numbers are assigned from 0-9 spreading East to West. The 4 was assigned ...