Canadian subnational postal abbreviations

Canadian provincial and territorial postal abbreviations are used by Canada Post in a code system consisting of two capital letters, to represent the 13 provinces and territories on addressed mail. These abbreviations allow automated sorting.

ISO 3166-2:CA identifiers' second elements are all the same as these; ISO adopted the existing Canada Post abbreviations.

These abbreviations are not the source of letters in Canadian postal codes, which are assigned by Canada Post on a different basis than these abbreviations. While postal codes are also used for sorting, they allow extensive regional sorting. In addition, several provinces have postal codes that begin with different letters.

The codes replaced the inconsistent traditional system used by Canadians until the 1990s. Apart from the postal abbreviations, there are no officially designated traditional (or standard) abbreviations for the provinces. Natural Resources Canada, however, maintains a list of such abbreviations which are recommended for "general purpose use" and are also used in other official contexts, such as the census conducted by Statistics Canada. Some of the French versions included a hyphen. Nunavut (created in 1999) does not have a designated abbreviation because it did not exist when these codes were phased out, though some can be found in other official works.

The sources of the postal abbreviations vary. Some are from the initials of two of the words in the name of a province or territory, while others are from the first and final letter or from the first and some other letter in the name. All of these names are based on the English form of the name, though they also correspond to their French equivalents in various ways (for example, NT could be read for the first and last letters of Nord-Ouest, instead of Northwest Territories). For Quebec and New Brunswick, the two provinces with large numbers of French-speakers, the initials in both languages are identical. French equivalents of each abbreviation once existed: see Traditional abbreviations.

...
Wikipedia