More information on Dissemination area (DA)

Censuses:

2006, 2001

Remarks:

Dissemination areas respect several delineation criteria designed to maximize their usefulness for data analysis and to meet operational constraints.

1. Dissemination area (DA) boundaries respect the boundaries of census subdivisions and census tracts. DAs therefore remain stable over time, to the extent that census subdivisions and census tracts do.
2. Dissemination area boundaries follow roads. DA boundaries may follow other features (such as railways, water features, power transmission lines), where these features form part of the boundaries of census subdivisions or census tracts.
3. Dissemination areas are uniform in terms of population size, which is targeted from 400 to 700 persons to avoid data suppression. DAs with lower population counts (including zero population) may result in order to respect the boundaries of census subdivisions and census tracts. DAs with higher population counts may also result.
4. Dissemination areas are delineated based on the block population counts from the previous census due to operational constraints.
5. Dissemination areas are compact in shape, to the extent possible while respecting the above criteria.
6. The number of dissemination blocks that are included in a dissemination area is limited to 99 due to operational constraints.

The coverage of 2006 dissemination areas can now be considered as fully national. All areas that were previously equal to the 2001 enumeration areas are delineated according to the above criteria.

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

Geographic proximity is embedded in the DA code by assigning DA codes in a serpentine manner within each census division.

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

Refer to the related definitions of dissemination block (DB); census subdivision (CSD) and census tract (CT), and to 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 dissemination area (DA) was a new standard geographic area. It replaced the enumeration area (EA) as a basic unit for dissemination. The 1996 population counts were used to delineate the DAs. The 2001 DAs were delineated only where sufficiently accurate block population counts existed, mainly in block-face geocoding areas of CMAs/CAs. Everywhere else, the 2001 EAs were the same as the 2001 EAs used for data collection.