What does z. i. p. stand for?

1 Answer

The "Z-I-P" in "ZIP Code" stands for "Zone Improvement Plan". It was introduced on July 1, 1963, as part of a larger plan by the U.S. Postal Ssrvice (USPS) to improve the speed of mail delivery. The USPS purposely chose an acronym that would itself imply quickness or speed.