How Is Mail Sorted?

Every hour in the U.S., more than 15 million pieces of mail are sorted and sent on their way. But the most interesting part isn’t the volume — it’s how little the system has changed since Benjamin Franklin oversaw it in 1775. The core idea is the same today as it was back then. What’s different is the speed. While Postmaster General Franklin ran the system by hand, today, technology has transformed mail sorting into a highly automated process.

From Collection to Carrier

Mail sorting begins the moment your letter to grandma hits the mailbox. That envelope travels to a USPS sorting facility where high-tech equipment has replaced hands to separate items by size and shape, a step called culling. Then, rather than a human orienting each piece of mail so the address is upright (called facing) and canceling the stamp to prevent reuse, systems such as the Advanced Facer Canceller System (AFCS) complete the task.

But the mail is nowhere near ready to ship. Next is the address recognition step. What early postal workers did manually — reading each address then using their knowledge of cities, routes, and post offices to organize letters into labeled pigeonholes — is now done with high-speed scanners, advanced software, and automated sorting machines. Scanners first capture images of each piece of mail, software then identifies the destination ZIP code. The mail receives a new barcode containing routing information, which is read by an automated machine that then sorts the mail into bins organized by destination. As the item moves closer to its final destination, it is typically processed through several facilities, with each stage reading the barcode and sorting the piece into increasingly specific groups — think state, city, neighborhood, street, house — following the same basic logic that guided mail sorting in Franklin’s time, but executed with far greater speed and precision.

At the final processing center, you guessed it, more machines perform the final round of sorting, often arranging mail in the exact order it will be delivered along a carrier’s route. So when the mail is sent to local post offices, carriers no longer need to hand-sort the mail according to their route. They simply pick it up and complete delivery — and the long wait for your package or postcard is over.