USPS mail: how does mails gets sorted and delivered across the country?

-Karthik Gurumurthy

Ever wonder how your letter magically travels across the country? It’s actually pretty wild when you think about it!

When you drop a letter in a mailbox in New York headed for LA, this whole invisible machine starts working. Your letter might reach the airport within 12 hours, and the processing centers in NYC alone handle a crazy 17 million pieces daily (with night being their busiest time).

Local mail usually arrives the next day, stuff to nearby states like Pennsylvania or Connecticut takes about two days, and coast-to-coast mail (NY to California) typically needs three days.

In LA, your letter gets routed from the airport to a processing center, then through sorting machines to your local post office. There, carriers arrive early morning, sort everything by building and street, and head out on their routes.

The sorting technology is pretty impressive – they introduced a nine-digit zip code system in 1981, and they have these advanced optical character readers (AOCRs) that process 40,000 pieces per hour! The only downside is they only work with standard business envelopes with typed addresses. By 1986, they upgraded half their sorting machines with these optical readers that scan zip codes and print bar codes on envelopes (just like grocery products).

At massive sorting centers like Morgan in Manhattan, they have 17 letter-sorting machines (LSMs), each with 12 consoles connected to 277 bins. Operators process one letter per second, punching in zip codes as letters whiz by on suction arms.