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Geographic Units:

Census Metropolitan Area (CMA) and Census Agglomeration (CA)

Modified on December 17, 2002

Part A – Plain Language Definition

Area consisting of one or more adjacent municipalities situated around a major urban core. To form a census metropolitan area, the urban core must have a population of at least 100,000. To form a census agglomeration, the urban core must have a population of at least 10,000.

Part B – Detailed Definition

A census metropolitan area (CMA) or a census agglomeration (CA) is formed by one or more adjacent municipalities centred on a large urban area (known as the urban core). The census population count of the urban core is at least 10,000 to form a census agglomeration and at least 100,000 to form a census metropolitan area. To be included in the CMA or CA, other adjacent municipalities must have a high degree of integration with the central urban area, as measured by commuting flows derived from census place of work data.

If the population of the urban core of a CA declines below 10,000, the CA is retired. However, once an area becomes a CMA, it is retained as a CMA even if the population of its urban core declines below 100,000. The urban areas in the CMA or CA that are not contiguous to the urban core are called the urban fringe. Rural areas in the CMA or CA are called the rural fringe.

When a CA has an urban core of at least 50,000 based on census counts, it is subdivided into census tracts. Census tracts are maintained for the CA even if the population of the urban core subsequently falls below 50,000. All CMAs are subdivided into census tracts.

Censuses: 2001, 1996, 1991, 1986, 1981, 1976, 1971, 1966, 1961, 1956, 1951, 1941

Remarks:

Delineation Rules for CMAs and CAs

A CMA or CA is delineated using adjacent municipalities (census subdivisions) as building blocks. These census subdivisions (CSDs) are included in the CMA or CA if they meet at least one of the following rules. The rules are ranked in order of priority. A CSD obeying the rules for two or more CMAs or CAs is included in the one for which it has the highest ranked rule. If the CSD meets rules that have the same rank, the decision is based on the population or the number of commuters involved. A CMA or CA is delineated to ensure spatial contiguity.

1. The Urban Core Rule: The CSD falls completely or partly inside the urban core.

A core hole is a CSD enclosed by a CSD that is at least partly within the urban core and must be included to maintain spatial contiguity. In Figure 25, CSDs A, B and C are included in the CMA or CA because of the urban core rule. CSD C is a core hole.

Figure 25. The Urban Core Rule

Figure 25. The Urban Core Rule

2. The Forward Commuting Flow Rule: Given a minimum of 100 commuters, at least 50% of the employed labour force living in the CSD works in the delineation urban core (see following note), as determined from commuting data based on the place of work question in the last decennial census (1991 Census).

Note: For CMA and CA delineation purposes, a delineation urban core is created respecting CSD limits. For a CSD to be included in the delineation urban core, at least 75% of a CSD's population must reside within the urban core. In Figure 26, CSD A is part of the delineation urban core since its entire population resides within the urban core. CSD B would also be part of the delineation urban core if at least 75% of its population resides within the urban core. For this example, we have assumed that less than 75% of the population of CSD B resides within the urban core; therefore, CSD B and its enclosed hole, CSD C, are not considered to be part of the delineation urban core.

Figure 26. The Forward Commuting Flow Rule

Figure 26. The Forward Commuting Flow Rule

3. The Reverse Commuting Flow Rule: Given a minimum of 100 commuters, at least 25% of the employed labour force working in the CSD lives in the delineation urban core as determined from commuting data based on the place of work question in the last decennial census (1991 Census). In Figure 27, at least 25% of the employed labour force working in CSD E lives in CSD A (see Note for Rule 2).

Figure 27. The Reverse Commuting Flow Rule

Figure 27. The Reverse Commuting Flow Rule

4. The Spatial Contiguity Rule: CSDs that do not meet a commuting flow threshold may be included in a CMA or CA, and CSDs that do meet a commuting flow threshold may be excluded from a CMA or CA.

Two situations can lead to inclusion or exclusion of a CSD in a CMA or CA for reasons of spatial contiguity. Specifically these are:

Outlier – A CSD (F in Figure 28) with sufficient commuting flows (either forward or reverse) is enclosed by a CSD (G in Figure 28) with insufficient commuting flows, but which is adjacent to the CMA or CA. When this situation arises, the CSDs within and including the enclosing CSD are grouped to create a minimum CSD set (F + G). The total commuting flows for the minimum CSD set are then considered for inclusion in the CMA or CA. If the minimum CSD set has sufficient commuting flows (either forward or reverse), then all of its CSDs are included in the CMA or CA.

Hole – A CSD (H in Figure 28) with insufficient commuting flows (either forward or reverse) is enclosed by a CSD (I in Figure 28) with sufficient commuting flows, and which is adjacent to the CMA or CA. When this situation arises, the CSDs within and including the enclosing CSD are grouped to create a minimum CSD set (H + I). The total commuting flows for the minimum CSD set are then considered for inclusion in the CMA or CA. If the minimum CSD set has sufficient commuting flows (either forward or reverse), then all of its CSDs are included in the CMA or CA.

Figure 28. The Spatial Contiguity Rule

Figure 28. The Spatial Contiguity Rule 

5. The Historical Comparability Rule: To maintain historical comparability for CMAs and larger CAs (those with census tracts in the previous census), CSDs are retained in the CMA or CA even if their commuting flow percentages fall below the commuting flow thresholds (Rules 2 and 3). See Figure 29.

Figure 29. The Historical Comparability Rule

Figure 29. The Historical Comparability Rule

An exception to the historical comparability rule is made in cases where CSDs have undergone changes to their boundaries, such as annexations. To determine whether to keep or exclude a CSD, place of work data are retabulated for the CSD with boundary changes, and a decision to include or exclude the CSD is made according to the previous rules.

6. Manual adjustments: A CMA or CA represents an area that is economically and socially integrated. However, there are certain limitations to the extent by which this ideal can be met. Since the CSDs that are used as building blocks in CMA and CA delineation are administrative units, their boundaries are not always the most suitable with respect to CMA and CA delineation. There are always situations where the application of the above rules creates undesirable outcomes, or where the rules cannot be easily applied. In these circumstances, a manual override is sometimes applied to ensure that the integrity of the program is retained. For example, in Sherbrooke CMA, the CSD of Compton Station, SD, which is in two parts, is included to maintain spatial contiguity.

7. Merging Adjacent CMAs and CAs: A CA adjacent to a CMA can be merged with the CMA if the total percentage commuting interchange between the CA and CMA is equal to at least 35% of the employed labour force living in the CA, based on place of work data from the decennial census. The total percentage commuting interchange is the sum of the commuting flow in both directions between the CMA and the CA as a percentage of the labour force living in the CA (i.e. resident employed labour force).

Merging Adjacent CMAs and CAs, formula.

If more than one CA is adjacent to the same CMA, each CA is assessed separately with the CMA. Several CAs may be merged with one CMA. If the total percentage commuting interchange is less than 35%, the CMA and CA are not merged.

After a CA is merged with a CMA, the urban core of the former CA is called the secondary urban core of the CMA.

Figure 30. Example of a Merged Census Metropolitan Area and Census Agglomeration

Figure 30. Example of a Merged Census Metropolitan Area and Census Agglomeration

 

Names and Coding Structure

CMA and CA names are usually based on the principal urban area or census subdivision (as of the census reference date) within the CMA or CA. Each CMA and CA is assigned a three-digit code that identifies it uniquely in Canada. The first digit is the same as the second digit of the province code in which the CMA or CA is located. If a CMA or CA spans a provincial boundary, then the province code assigned represents the province with the greater proportion of urban core population. Codes for CMAs or CAs in the Yukon Territory and the Northwest Territories begin with the same digit as for those CMAs or CAs located in British Columbia. There are currently no CMAs or CAs in Nunavut.

CMA/CA Code

CMA/CA Name

001
215
462
995

St. John's CMA (Nfld.Lab.)
Truro CA (N.S.)
Montréal CMA (Que.)
Yellowknife CA (N.W.T.)

If data for provincial parts are required, it is recommended that the two-digit province code precede the CMA/CA code for those CMAs/CAs that cross provincial boundaries. For example:

PR-CMA/CA Code

CMA/CA Name

24 505
35 505
47 840
48 840

Ottawa–Hull CMA (Que.)
Ottawa–Hull CMA (Ont.)
Lloydminster CA (Sask.)
Lloydminster CA (Alta.)

Changes to the Number of CMAs and CAs for the 2001 Census

Table 1 in the Introduction shows the number of census metropolitan areas and census agglomerations by province and territory.

Two CAs from the previous census became CMAs: Kingston, Ontario and Abbotsford, British Columbia.

Seven new CAs were created: Amos, Que., Amherstburg, Ont., Caledon, Ont., Petawawa, Ont., Brooks, Alta., Squamish, B.C. and Parksville, B.C. However, the Amherstburg CA was then merged with the Windsor CMA due to its high commuting interchange with that CMA, and similarly the Caledon CA was merged with the Toronto CMA.

The 1996 CA of Strathroy merged with the CMA of London after the City of Strathroy amalgamated with the township of Caradoc to become the township of Strathroy–Caradoc, which is adjacent to the London CMA.

One CA (Smiths Falls, Ont.) was retired because the population of its urban core dropped below 10,000 in 1996.

Prior to 2001, adjacent CMAs and CAs that had sufficient commuting interchange to be merged (35% or more) were identified by the terms "primary census metropolitan area (PCMA)" and "primary census agglomeration (PCA)". The terms "consolidated census metropolitan area" and "consolidated census agglomeration" described the sum of the component CMAs and CAs. Census data were disseminated for these areas. These terms will not be used for the standard dissemination program for 2001. The 1996 Census Dictionary (Catalogue No. 92-351-XIE) provides further details about these discontinued terms.

Refer to the Geography Working Paper Series, Catalogue No.92F0138MIE2002001 for more detailed information about changes to CMAs and CAs for the 2001 Census.

Data Quality

CMAs and CAs are statistically comparable because they are delineated in the same way across Canada. They differ from other areas such as trading or marketing areas, or regional planning areas designated by regional authorities for planning and other purposes, and should be used with caution for non-statistical purposes.

The CSD limits used in CMA and CA delineation are those in effect on January 1, 2001 (the geographic reference date for the 2001 Census) and received by Statistics Canada before March 1, 2001. In addition, CMA and CA delineation uses commuting data based on the place of work question asked in the decennial census. Thus, the 2001 and 1996 CMAs and CAs are based on population and place of work data from the 1991 Census. The 1991 and 1986 CMAs and CAs were based on the data from the 1981 Census.

Users should be aware that the Canadian CMA/CA program differs from the metropolitan statistical area program in the United States. Although the delineation methodologies are similar, the entry point for the U.S. metropolitan area program is lower – any urban core of 50,000 or more would be recognized as a CMA in the U.S.

Refer to the related definitions of Census Subdivision (CSD), Urban Area (UA), and Urban Core, Urban Fringe and Rural Fringe.

Changes Prior to the 2001 Census:

For more information, refer to Paper No. 2002-1 of the Geography Working Paper Series, entitled "Census Metropolitan Areas and Census Agglomerations with Census Tracts for the 2001 Census" and written by Peter Murphy and Henry Puderer (Catalogue No. 92F0138MIE).

1996

Two changes to CMA/CA delineation rules were implemented to preserve data comparability over time. CMAs could be consolidated with CAs, but they could not be consolidated with other CMAs. A primary census agglomeration (PCA) could not be retired from a consolidated CMA or CA (with census tracts at the previous census) even if its total commuting interchange percentage dropped below the consolidation threshold of 35%. Exceptions to this rule could occur due to changes in the physical structure of the urban areas used to determine the urban cores.
  Minimum sets of CSDs were used instead of the census consolidated subdivisions (CCSs) for evaluation in the spatial contiguity rule. Refer to the Spatial Contiguity Rule (point 4).
     
1986 Introduction of the consolidated and primary CMA and CA concept.
  The forward commuting threshold was raised from 40% to 50% to control for differences in processing of the place of work data between 1971 and 1981.
  Introduction of the minimum of 100 commuters for forward and reverse commuting for both CMAs and CAs.

 

Single CSD (component) CAs were permitted.
     
1981 Commuting data based on the place of work question of the previous decennial census were used for the first time to delineate CAs. For both CMAs and CAs, the forward commuting threshold was 40% and the reverse commuting threshold was 25%.
  The minimum urbanized core population for CAs was raised from 2,000 to 10,000.

 

CAs were eligible for census tracts if they had a CSD with a population of at least 50,000 at the time of the previous census. Single CSD (component) CAs could be created for subdivision into census tracts.
     
1976 Commuting data based on the place of work question of the previous decennial census were used for the first time to delineate CMAs. The forward commuting threshold was 40% and the reverse commuting threshold was 25% for the CMAs.

 

For CAs, see 1971.
     
1971 CMAs were defined as main labour market areas, but were delineated according to alternate criteria based on the labour force composition, population growth rate and accessibility. At this time, the CMA of Saint John, N.B. was "grandfathered".

 

CAs were comprised of at least two adjacent municipal entities. These entities had to be at least partly urban and belong to an urbanized core having a population of at least 2,000. The urbanized core included a largest city and a remainder, each with a population of at least 1,000, and had a population density of at least 1,000 per square mile (386 persons per square kilometre).
     

1966

See 1961.
     
1961 CMAs were delineated around cities with a population of at least 50,000, if the population density and labour force composition criteria were met, and the total CMA population was at least 100,000.

 

CAs were called major urban areas; see 1951.
     
1956 See 1951.

 

 
1951 The term "census metropolitan area" appeared for the first time. This term designated cities of over 50,000 having fringe municipalities in close geographic, economic and social relations, the whole constituting a unit of over 100,000.

 

The concept of "major urban areas", the forerunners to CAs, was introduced. The term designated urban areas in which the largest city had a population of at least 25,000 and fewer than 50,000.
     

1941

Data were published for "Greater Cities", i.e. those cities which have well-defined satellite communities in close economic relationship to them.

 
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