Distribute Zip Code Release For Free

To develop this nationwide code, the Post Office Department looked to a sorting system that it had started using in a limited capacity in 1943. This system divided up large cities into multiple 2-digit postal zones, which were written by mailers in the lower line of addresses and called local zone numbers.

ZIP Codes are numbered with the first digit representing a certain group of U.S. states, the second and third digits together representing a region in that group (or perhaps a large city) and the fourth and fifth digits representing a group of delivery addresses within that region.

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.

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.

The first digit of a five-digit ZIP Code divides the United States into 10 large groups of states (or equivalent areas) numbered from 0 in the Northeast to 9 in the far West. Within these areas, each state is divided into an average of 10 smaller geographical areas, identified by the second and third digits.

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.

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.