ZIP is an acronym that stands for "Zone Improvement Plan." ZIP Code" numbers are extremely important in the processing and delivery of mail. Using the correct ZIP+4® code reduces the number of handlings and significantly decreases the potential for error and possibility of misdelivery. The nine digits of a ZIP+4 code (e.g., 12345-6789) may be grouped as follows: [123] [45] ?" [67] [89 ] [123] : Sectional Center or Large City [45] : Post Office" facility or Delivery Area ?" : The required "dash" or "hyphen" separates the first five digits from the last four digits; the +4 [67] : Sector or Several Blocks [89] : Segment or One Side of a Street Note: If ND appears in place of the ZIP+4®, it has not yet been assigned/designated for the area (use 5-digit ZIP).
