The history of ZIP codes in the United States dates back to the early 1960s. ZIP stands for "Zone Improvement Plan" and was introduced to improve the efficiency of mail delivery and sorting processes. Here's a brief overview of the history of US ZIP codes:
Early Postal System: Prior to ZIP codes, the United States had a postal system that relied on city names, street names, and house numbers for mail sorting and delivery. However, as the country grew and urban areas expanded, this system became increasingly complex and inefficient.
Zoning Improvement Plan: In 1943, an interdepartmental committee, led by postal inspector Robert Moon, proposed a numerical coding system to simplify mail processing. This idea gained traction, and by the early 1960s, the United States Postal Service (USPS) started developing a new system called the Zone Improvement Plan (ZIP).
Introduction of ZIP Codes: On July 1, 1963, the USPS officially introduced ZIP codes in the United States. The initial system consisted of five-digit codes that represented specific geographic regions. The first digit represented a broad area, while subsequent digits narrowed down the location further. This allowed mail to be sorted more efficiently.
A Sectional Center Facility (SCF) sorts mail to all post offices with those first three digits in their ZIP Codes. The mail is sorted according to the final two digits of the ZIP Code and sent to the corresponding post offices in the early morning. Sectional centers do not deliver mail and are not open to the public (although the building may include a post office that is open to the public), and most of their employees work the night shift. Items of mail picked up at post offices are sent to their own SCFs in the afternoon, where the mail is sorted overnight. In the case of large cities, the last two digits as assigned generally coincided with the older postal zone number.
Expansion and Introduction of ZIP+4: Over time, the ZIP code system expanded to cover the entire country. In 1983, the USPS introduced ZIP+4, which added four additional digits to the standard five-digit ZIP code. The extra digits helped pinpoint specific addresses and improved mail sorting accuracy.
ZIP Code Database: To facilitate the implementation of ZIP codes, the USPS created a comprehensive database of codes and corresponding address information. This database is regularly updated to reflect changes in addresses and ZIP codes.
ZIP Code Benefits: ZIP codes have brought several benefits to mail delivery and related services. They enable automation in mail processing, expedite sorting, and improve accuracy. ZIP codes also aid in demographic analysis, marketing research, and targeted mail campaigns.
ZIP Code Evolution: Over the years, ZIP codes have undergone changes to accommodate population growth, regional expansions, and changes in postal infrastructure. Some areas have had ZIP code splits or boundary adjustments to better manage mail distribution.
It's worth noting that while ZIP codes are primarily used for mail sorting and delivery, they have also become a widely used means of geolocation and are often referenced in various contexts beyond postal services, such as demographic studies, mapping, and online services.