Dictionary, Census of Population, 2021
Figure 1.6
Delineation Core rule

Figure 1.6 is a graphical representation of the delineation core rule (rule 1^{Note 1}) for delineating a census metropolitan area (CMA). A fictional grouping of 12 census subdivisions (CSDs), shown as polygons labelled 'A' through 'L,' represent the group of CSDs that could form a CMA.

All of CSD A and a small portion of the adjacent CSDs B and J are shaded to represent a population centre. This population centre also makes up the core of the CMA. Since CMAs are built on CSDs, all of CSDs A and B are included in the CMA because of the delineation core rule. Since less than 50% of the CSD J population is located in the core, this CSD is not part of the CMA under the delineation core rule and will therefore be available for the other subsequent delineation rules. Census subdivision D has a small, shaded polygon within it that identifies a population centre that is not part of the core and is therefore referred to as fringe.

Census subdivision K is a small CSD that exists within the larger CSD B. This core hole, i.e., CSD K, is not considered to be part of the delineation core because it does not have at least 50% of its population living in the core. CSD K will therefore be available for the other subsequent delineation rules.

A thick black line outlines the perimeter of CSDs A, B and excludes CSD J and K, leaving a hole, to identify the boundary of the CMA.

Two legends appear below the figure. The legend on the left identifies the symbols used in the figure to represent the boundaries of the CMA, CSD, population centre, core and fringe. The legend on the right distinguishes which CSDs are included in the CMA according to their inclusion criteria. For this figure, CSDs A and B are included under rule 1 (delineation core rule).

Source: Statistics Canada, 2021 Census of Population.