By the early 1960s, the swelling volume of mail was taxing the Post Office Department to its limits. Zoning Improvement Plan—ZIP—Codes were one response to this growing mountain of mail. Using numbers to stand for regions, cities, post offices, or even city neighborhoods made it easier sort the mail—by machine or by hand. Today ZIP codes are used to help shape everything from voting districts to marketing campaigns.
What Do the Codes Represent?
Think of each 5-digit ZIP Code as a group of addresses. They might be homes or businesses, schools or apartment houses. One 5-digit number might represent 10,000 delivery points—spread out over many miles in a rural area or concentrated in a few city blocks.
What Does Each Number Mean?
The first digit represents a region of the country. The next two digits stand for a central post office facility in the region. The last two digits represent a post office or a postal zone. So, the ZIP Code 97403 means the west coast & Pacific, Eugene mail center, and the University of Oregon.
“Swingin' Six” ZIP Code Video