The history of Canadian postal codes
The history of Canadian postal codes largely follows that of the American ZIP code, but predate the evolution of the ZIP code by quite a few years. Canada began using numbered postal zones within Toronto in the mid-1920s, which rapidly grew and in less than 20 years required 14 postal zones within the City of Toronto. Urban growth elsewhere required this same system to be adopted and, in the late 1960s, Canada Post (then known as the Post Office) started to develop three digit number zones to cover the majority of Canadian cities, which effectively did away with the single or double digit postal zone.
As would be expected, Toronto was the first Canadian city to have this system put into practice. Digits between 100 and 799 were assigned throughout the Metropolitan area, which gave Canada Post the flexibility to effectively route mail to some of Toronto smaller suburbs and outlying areas. The system proved to be effective and was expanded to other major Canadian cities on May 1, 1969. However, the system lasted less than a year before the official Canadian postal code system was put into place.
The postal code system was met by quite a bit of resistance by the Canadian Union of Postal Workers. When it was introduced, it was shortly followed by the automated sorting system, which was able to read postal codes and ensure a speedier flow of sorting. This led to a near two year job action that started in March 1974 and ended in February 1976. During this time, postal workers promised that those who did not use postal codes would have their mail given preferential treatment at the standard stamp rate due to layoffs being expected. However, the automated system proved to be a revenue generator for Canada Post and allowed them to compensate union members for their losses. The system continued and has remained relatively unchanged since then.
Canadian postal codes are still in use today. They're marked by a six-character string of letters and numbers, which precisely route mail to specific neighbourhoods within cities in Canada; and are usually accurate enough to pinpoint the exact street. There are over 843,000 postal codes recognized by Canada Post.