The modern zip code idea began in 1962 and was put into minimum use in 1963 on July 1. The name ZIP is an abbreviation for Zoning Improvement Plan. The original coding assigned a five digit code to cover specific every address in the country. The first number was a wide geographical area with 0 beginning in the Northeast and 9 ending in the outlying West. The next two digits sophisticated the general are to smaller regions that had major haulage access. The last two digits tapering the area to smaller post offices or postal zones in larger cities. At the start, use of the new code was not obligatory for anyone, but, in 1967, the Post Office required mailers of second and third class bulk mail to pre-sort by ZIP Code. Although the public and mailers alike adapted well to its use, it was hurriedly palpable that the idea was not enough.

US Postal Service began using a prolonged ZIP Code called "ZIP+4." A ZIP+4 codes consist of the original five digits ZIP Code plus a four digit add-on code. The four digit affix number identifies a geographic division within the five digit delivery area, such as a city block, office building, individual high-volume receiver of mail, or any other unit that would aid efficient mail sorting and delivery. But it helps the Postal Service direct mail more resourcefully and precisely because it reduces handling and appreciably decreases the potential for creature error and possibility of misdelivery. It also will escort to better control over USPS costs and, in turn, postage rate stability. ZIP+4 is intended for use primarily by business mailers who prepare their mail with typewritten, machine-printed, or computerized addressing formats that can be read by the Postal Service's automated scanners during processing.

These measurements are approximately the geographical center of the zip code coverage. Some are taken at airports and some at government facilities, such as nationalized parks, fire stations, weather stations, military installations and navigational facilities. Enter the five digit Zip Code and click on Lookup. This data is from the US Geological Survey mapping service but is resident on our server and available for purchase if desired. The information will be displayed in a separate window that you can close when finished. If you are looking to find a zip code, try the USPS information base. They also have many useful web tools available online.