US Postal Inspection Service on Instagram: "As America’s first federal agents, Postal Inspectors have protected the mail, the U.S. Postal Service, and the American public for over 250 years. 📬 #USPIS250"

Explaining on Instagram: "The ZIP code system was introduced in the United States in 1963 under the “Zone Improvement Plan.” It was created to keep up with the nation’s booming population and growing mail volume, which had outpaced older methods of sorting and delivery. Before ZIP codes, postal workers relied on personal knowledge of neighborhoods to route letters and packages, a system that quickly became outdated as cities expanded and suburbs spread. The five-digit ZIP brought order to the ch