Mapping the Zip Code

The zip code system designates postal delivery points within the United States. A zip code is a five digit number that relates to a specific postal district. Each of the digits in that number provides an increasingly more precise delivery point. The first digit in a zip code number designates a specific group of U.S. states. The second and third digits together represent a region or a large city within that group. The fourth and fifth digits indicate a specific group of delivery addresses within that region.

You can get a great idea of how the zip code system works using Zip De-Code. Zip De-Code is an interesting mapped visualization of every single zip-code area in the USA. Every dot on the Zip De-Code map is one zip code delivery area. If you type in the individual digits of a zip code number, one by one, into Zip De-Code then the map automatically updates to show only the dots representing the zip code delivery points indicated by the digits you have entered.


For example, if you type in the first digit of the zip code '90210', then you can view a dot map of all the zip code delivery points in the USA which start with a '9'. If you then type in '0' the dots on the map reduce to show only the delivery points starting with '90'. As you continue to type in the whole five digit number, '90210' the map continues to zoom in until it eventually shows only one dot representing the delivery point for Beverley Hills in California.