The US Postal Service is often one of the first places where new technology is put to use. It has invested largely in Optical Character Recognition technology, and currently 88% of all processed mail is imprinted with a barcode, allowing for efficient, mechanical sorting. The OCR technology has advanced far enough that even handwritten addresses can be read. Currently the USPS is investing in robotic systems that unload mail for transport, replacing the need for manual labor in that area. Use of the ZIP+4 system has helped increase the efficiency of mail sorting. For mail which does not include the extra four digits, computers with Optical Character Recognition technology can read the address and determine what the extra four digits should be by looking up the address in a database. There has even been an experimental 11-digit ZIP Code. By using this system, computers could sort mail not only by where it is going, but also in what order it is to be delivered. This eliminates the need for mail carriers to constantly shuffle mail around during delivery.