How the Post Office Works

Currently, the Post Office is the second largest employer in the United States, providing jobs to over 663,000 people. The U.S. Postal Service (USPS) delivers more mail to a wider geographical area than any other country's postal system in the whole world. The more than 203 billion parcels of mail handled by the U.S. Post Office in 2008 breaks down to around 463,000 parcels processed each minute. The workload is spread out over 32,741 post offices across the nation. The whole USPS operates under an intricate system.

The Post Office employs the U.S. Postal Inspection Service to secure and inspect the mail system. This service takes the initiative in protecting the American public from many scams that involve counterfeit checks. The service also works to educate the public on schemes that set out to rip off consumers. Over 9,000 arrests were made in 2008 involving people committing crimes through the USPS.

Essential to efficient handling of mail is the use of Zoning Improvement Plan (ZIP) codes. This system was employed in 1963 and is used to better handle large volumes of mail. The first digit in a ZIP code connotes United States geography, with a “0” indicating East Coast locales all the way up to “9” referring to areas along the West Coast. The two numbers that follow relate to specific regions while the last two numbers represent specific post offices across the nation. The four numbers that follow a ZIP code indicate specific street groups or high-rise buildings. The addition of the extra four numbers was adopted in 1983.

Many processes through the USPS are automated while the rest are carried out by hand. The Intelligent Mail system uses bar codes located on parcels that identify what a particular piece of mail is and tracks it through the system. The Flats Sequencing System is technology that sorts “flats,” or magazines and large envelopes. The Delivery Input and Output Subsystem verifies addresses and prints on the mail a bar code that is used for sorting. The machines used by the U.S. Postal Office can read up to 93 percent of all mail that is hand-addressed. The Postal Automated Redirection System forwards mail to people who have registered their address changes. Most of the postal system is automated but it will always need people to operate properly.

Outgoing mail is placed in mailboxes that are emptied by postal employees. This mail is gathered in a truck and delivered to the local post office. Once there, the majority of the mail is sorted by machines. The Advanced Facer Canceller System puts all parcels of mail in one direction and verifies stamps. The Delivery Bar Code Sorter sorts mail and reads any present bar code. Any package and bundle of mail that comes through gets processed by the Automated Package Processing System. Once properly sorted, parcels are then shipped out via truck or airplane to the proper regional post office. When they arrive, they are further sorted into a specific area or route taken by a postal delivery person. That postal employee delivers mail by hand to its proper destination.