The monthly mean minimum and maximum temperatures over the year in Stockholm, Sweden. Show the average temperatures in Stockholm in Celsius Â» Data from nearest weather station: Stockholm, Sweden (0.0 Miles).
The postal service started the use of postal zones for large cities in 1943. By the early 1960s a more general system was needed. On July 1, 1963, ZIP codes were created for the whole country but they were not mandatory. In 1967, these were made mandatory for many types of mail. The system was soon used for all mail.
ZIP Code. 1  During World War II, thousands of experienced postal employees left to serve with the military. To offset the loss, in May 1943 the Post Office Department began a zoning address system in 124 of the largest cities. 2  Twenty years later, the Department implemented an even farther reaching plan, the Zoning Improvement Plan (ZIP) Code. The social correspondence of the 19th century had given way, gradually then explosively, to business mail. By 1963, 80 percent of all mail in the United States was business mail.