Forward sortation areas[]
A forward sortation area (FSA) is a geographical region in which all postal codes start with the same three characters. The first letter of an FSA code denotes a particular "postal district", which, outside of and , corresponds to an entire . Owing to Quebec's and Ontario's large populations, those two provinces have three and five postal districts respectively, and each has at least one urban area so populous that it has a dedicated postal district ("H" for the, and "M" for ). On the other hand, the low populations in and the (NWT) mean that even after Nunavut separated from the Northwest Territories and became its own territory in 1999, they continue to share a postal district. The digit specifies if the FSA is urban or rural. A zero indicates a wide-area rural region, while all other digits indicate urban areas. The second letter represents a specific rural region, an entire medium-sized city, or a section of a major metropolitan area.
is provided, divided into separate articles by postal district. Individual FSA lists are in a tabular format, with the numbers (known as zones) going across the table and the second letter going down the table. The FSA lists specify all communities covered by each rural FSA. Medium-sized cities may have one dedicated FSA, while larger cities have more than one FSA within their limits. For FSAs spanning more than one city, the city which is allocated the most codes in each such FSA is listed. For cities with a small number of FSAs (but more than one), the lists specify the relative location of each FSA in those cities. For cities with a large number of FSAs, applicable neighbourhoods and boroughs are specified.
Local delivery units[]
The last three characters denote a local delivery unit (LDU). An LDU denotes a specific single address or range of addresses, which can correspond to an entire small town, a significant part of a medium-sized town, a single side of a city block in larger cities, a single large building or a portion of a very large one, a single (large) institution such as a university or a hospital, or a business that receives large volumes of mail on a regular basis. LDUs ending in zero correspond to postal facilities, from and small franchised retail postal outlets all the way up to sortation plants. In urban areas, LDUs may be specific postal carriers' routes. In rural areas where direct door-to-door delivery is not available, an LDU can describe a set of post office boxes or a . LDU 9Z9 is
used exclusively for . In rural FSAs, the first two characters are usually assigned in alphanumerical order by the name of each community.
LDU 9Z0
refers to large regional distribution centre facilities, and is also used as a
placeholder, appearing in some regional postmarks such as the "K0H 9Z0" which formerly appeared on purely local mail within the area.
Postal codes do not include the letters D, F, I, O, Q or U, and the first position also does not make use of the letters W or Z. This means the maximum number of FSAs available is 3,600. With 2,000 possible LDUs in each FSA, there is a theoretical limit of 7.2 million postal codes. The practical limit is a bit lower, as Canada Post reserves some FSAs for special functions, such as for test or promotional purposes, (e.g. the H0H 0H0 for Santa Claus, see below) as well as for sorting mail bound for destinations outside Canada. The current Statistics Canada estimate of over 830,000 active postal codes[20] represents about 12% of the entire postal code "space", leaving more than ample room for expansion.
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