Why are zip codes deprecated in the US Zip Codes Database?

The decision to deprecate zip codes is primarily driven by the USPS, which oversees the routing of mail. Zip codes may be decommissioned due to various reasons, including the closure or relocation of Post Offices, PO Boxes with dedicated zip codes, changes in the business landscape leading to the closure or relocation of single-business zip codes, and fluctuations in the US military presence, as certain zip codes are designated for mail delivery to the US Armed Forces.

It's important to note that the majority of these changes are minor and have minimal impact on mail delivery. Popular zip codes, for which demographic data from the Census is available, are generally unaffected by these adjustments.