Regulate Zip Code Bulletin For Free

It is preferred that all City, State, and ZIP Code information be on a single line. If that is not possible, the ZIP Code, including the ZIP+4 Code, may be placed below the city/state information. However, when compressing line #11, do not remove the hyphen between the ZIP Code and the ZIP+4 add-on code.

This is because ZIP code boundaries are based on mail routes and delivery points rather than geographic factors. The U.S. Post Office Department, predecessor to USPS, developed a zoning address system in 1943 as a way to make sorting and delivery of mail easier.

ZIP Codes were created to expedite mail processing, not to identify neighborhoods or regions. Their boundaries are based on the logistical and transportation needs of the United States Postal Service and not on neighborhoods, watersheds, or community cohesion.

So what do the extra numbers mean? These last 4 digits represent specific delivery routes within delivery areas. This extra detail means an even more precise matching to a more granular level. It could represent a handful of houses on one side of a street, or even a single building that receives a high volume of mail.

The standard ZIP code notation used by the United States Postal service uses five digits to identify a delivery area. An example of a standard US ZIP code is 90210.

Here's how the postal code system in Canada works. The first three digits are the forwarding station. The first letter does indicate the province. The next digit, a number, indicates whether the property is urban or rural.

A United States postal code, for example, might be either five digits or five digits followed a hyphen (dash) and another four digits (12345-1234).