Establish Zip Code Release For Free

There are no duplicate ZIP Codes. There are some ZIP Codes that are multi-part polygons, but those polygons are usually adjacent.

What each number means. The first digit designates a broad area, which ranges from zero for the Northeast to nine for the far West. The two following digits are the code of a central post office facility in that region. The last two digits designate small post offices or postal zones.

A ZIP code is the term used to describe the postal code system in the United States. It is a series of numbers that communicates information about people within different geographic groupings. There are two ZIP code systems within the United States, ZIP and ZIP+4.

The first digit is assigned to a broad geographical area of the United States, ranging from zero in the Northeast to nine in the West. The next two digits pinpoint population concentrations and sectional centers accessible to common transportation networks.

The prehistory of the ZIP code You might have used the recipient's street address along with the city and state, but you wouldn't have seen a ZIP code. Mail was hand-sorted, and delivery relied on local knowledge of its intended destination.

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.

Due to an increase in population or to the improve postal operations, the US Postal Service® will occasionally add a new ZIP Code or change ZIP Code boundaries.