A ZIP Code is a five-digit numerical code defined by the U.S. Postal Service (USPS) to simplify and expedite mail distribution. The United States is divided into 10 large geographical areas, with the first ZIP code digit 0 in the northeast and 9 in the west. The second and third digits are used to divide states, while the fourth and fifth digits represent local delivery areas.
ZIP+4 codes provide a more precise means of mail delivery by appending four additional digits to the standard five-digit ZIP code. This enhancement supports greater efficiency and accuracy for business mailers.
