Step 1 : Introduction to the question "When were ZIP codes officially implemented by the U.S. Post Office?"
...The concept of ZIP codes was first introduced during World War II. The U.S. Postal Service lost a large portion of its staff to the military buildup of World War II. The post office needed a way for its understaffed postal delivery service to work effectively. ZIP codes, or Zoning Improvement Plan, were officially implemented in 1963. The initial ZIP codes consisted of only two numbers. The first indicated the city and the second denoted the state. As delivery expanded across the nation, so did the concept of ZIP codes. By 1963, a ZIP code carried numerous bits of information: the area, the regional postal facility and the local zone. Source: WomansDay.com
