ZIP+4 Codes are the last 4 digits of a nine-digit ZIP Code. Some people don’t know that zip codes are actually longer than 5 digits. The 9-digit ZIP Code is made of two different parts. The first part is the first five digits of the zip code which indicates the destination post office or delivery area. This is the part of the zip code that everyone is aware of. The last 4 digits of the nine-digit ZIP Code represent a delivery route within a specific delivery area. When you use all 9-digits of full zip code, it assists the USPS in sorting and delivering the mail.
Interested in finding out the ZIP+4 code for a specific address? You can do that now by using our free Zip+4 Lookup Tool.
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USPS five-digit zip codes are the zip codes you are familiar with. Examples are 92019 or 84604. The 5 digit zip code most commonly indicates a destination post office.Here’s how it works:
A ZIP+4 code uses the basic five-digit code plus four additional digits to identify a geographic segment within the five-digit delivery area, such as a city block, a group of apartments, an individual high-volume receiver of mail, a post office box, or a specific delivery route — meaning the actual path the mail truck would travel could have changed.
Because they are based on delivery routes instead of more permanent boundaries, the last 4 digits of a complete ZIP code can change often. Five-digit ZIP codes also change, but they do so infrequently. Not so for ZIP+4. The +4 on a ZIP code can be changed as frequently as once a month, based on things like how many postal employees are working, who is working what route, etc.
A ZIP code is a postal code used by the United States Postal Service (USPS) in a system it introduced in 1963. An extended ZIP+4 code was introduced in 1983 which includes the five digits of the ZIP code, followed by a hyphen and four additional digits that reference a more specific location. However, initial attempts to promote universal use of the new format met with public resistance, and today the +4 code is not required. In general, mail is read by a multiline optical character reader (MLOCR) that almost instantly determines the correct ZIP+4 code from the address — along with the even more specific delivery point — and sprays an Intelligent Mail barcode (IM) on the face of the mail piece that corresponds to 11 digits — nine for the ZIP+4 code and two for the delivery point.
ZIPCODE DATA SINCE 2002