The need for postal codes for Nigerian states cannot be over emphasized. Can you imagine a situation where you are asked to fill a simple form as a graduate and you are confused on what the post code for Lagos or your state is, pending where you are resident.
A postal code (also known locally in various English-speaking countries throughout the world as a postcode, post code, Eircode, PIN Code or ZIP Code is a series of letters and/or digits, sometimes including spaces or punctuation, included in a postal address for the purpose of sorting mail.
In February 2005, 117 of the 190 member countries of the Universal Postal Union had postal code systems.
Although postal codes are usually assigned to geographical areas, special codes are sometimes assigned to individual addresses or to institutions that receive large volumes of mail, such as government agencies and large commercial companies. One example is the French CEDEX system.
To clear the confusion, here is the list of postal codes for all states and cities in Nigeria.