ZIP Code is a code system used to speed the sorting and delivery of mail in the United States. The name stands for _Z_one _I_mprovement _P_lan.
The ZIP system uses five numerals that appear after an address. In the ZIP number 22207, for example, the first numeral—2—designates one of 10 geographic areas. Area 2 consists of the District of Columbia, Maryland, North Carolina, South Carolina, Virginia, and West Virginia. The second two numerals—22—indicate a metropolitan area or sectional center. In this case, the mail is going to the Arlington area of Virginia. The last two numerals—07—represent a small town or delivery unit from which the mail will be delivered. In 1983, the Postal Service introduced a voluntary nine-number ZIP Code. High-volume business mailers that use this code receive a discount on their mailing rate.
The Post Office Department (now the United States Postal Service) introduced the ZIP Code in 1963. By that time, the volume of the mail in the United States had increased almost 900 percent since 1900. The mail had also changed in nature from chiefly personal to about 80 percent business correspondence.
Many companies use mechanized addressing systems. To help them, the Post Office Department in 1963 introduced two-letter abbreviations for states and some other areas. These abbreviations enable mechanized addressing systems to save space by putting a ZIP Code on the same line of an address as the city and state. For the two-letter state abbreviations, see Postal Service, United States (table: U.S. Postal Service abbreviations for states) .
The ZIP Code especially speeds up the handling and delivery of bulk mail (a huge number of identical pieces). Several other nations also use code systems.
