The postal zoning system in the United States began in 1943 with the introduction of the one or two digit zone number. These numbers identified a delivery station of a metropolitan post office. On July 1,1963, Mr Zip introduced the Zone Improvement Plan. This was a five digit national coding system used to identify each postal delivery section. The first digit identifies one of ten geographical areas, with the second digit denoting a state, part of a heavily populated state, or two or three less populated states. The third digit designates a major metropolitan postal facility or sectional center, with the fourth and fifth digits picking up the original zone number. The Federal German Post Office became the first to use the current postal code system to speed delivery. The function of a code system is to help in address scanning and the automated processing of mail, and to speed up mail sorting. Approximately 97 percent of all mail delivered in the United States uses the Zip Code. In 1974, the United States Postal Service issued a postage stamp to publicize the numerical system. The Zip Code, the numerical system, was publicized in ______.