More information on Dissemination block (DB)

Censuses:

• 2006 (dissemination block)
• 2001 (block)

Remarks:

The dissemination block (DB ) is the basic geographic area in the Spatial Data Infrastructure (SDI ).

Because dissemination blocks are primarily an artefact of the road network, the number of DBs created is a function of the currentness of the road network prior to the census. It is not possible to have a road network reflecting exactly the situation on Census Day. For the 2006 Census, the road network used for DB creation is up-to-date as of spring 2005.

Highway medians, ramp areas and other irregular polygons may form dissemination blocks on their own. A morphological dissemination block is split to form two or more DBs wherever it is traversed by the boundaries of selected standard geographic areas, namely federal electoral districts (FEDs ), census subdivisions (CSDs), census tracts (CTs), designated places (DPLs) or dissemination areas (DAs). This makes it possible to aggregate dissemination block data to all standard geographic areas.

In rural areas where the road network is sparse or even non-existent, the boundaries of collection units (CUs) are used to avoid creating very large dissemination blocks.

Each dissemination block is assigned a two-digit code. In order to uniquely identify each dissemination block in Canada, the two-digit province/territory code, the two-digit census division (CD) code and the four-digit dissemination area (DA) code must precede the DB code. For example:

Only population and dwelling counts are disseminated at the dissemination block level (with the dissemination area being the smallest standard geographic area for which characteristic data are disseminated). To ensure confidentiality, population counts are adjusted for dissemination blocks having a population of less than 15.

Table 1 in the Introduction shows the number of dissemination blocks by province and territory.

Refer to the related definitions of census division (CD); census subdivision (CSD); census tract (CT); designated place (DPL); dissemination area (DA); federal electoral district (FED); Spatial Data Infrastructure (SDI) and the geography working paper Introducing the Dissemination Area for the 2001 Census: An Update (Catalogue no. 92F0138MIE2000004).

Changes prior to the current census:

In 2001, the term 'block' was used.

Prior to 2001, households and their associated population and dwelling counts were geographically referenced to the enumeration area at the time of collection.