The USPS Bar Code

• The USPS uses a bar code that is printed underneath the address information.
• The bar code encodes the ZIP code (or ZIP+4, or ZIP+4+2 code).
• The bar code is intended to be read by a scanner.
• The ZIP code determined by the scanner is used in automated mail sorting facilities to route pieces of mail.
• In an abstract sense we can think of this process as a communication system.
• The transmitter is the bar code printer and the receiver is the scanner.

  

Figure 2.17: Envelope with USPS bar code.