Dictionary, Census of Population, 2021
Population centre (POPCTR)

Definition

A population centre (POPCTR) has a population of at least 1,000 and a population density of 400 persons or more per square kilometre, based on population counts from the current Census of Population. All areas outside population centres are classified as rural areas.

Taken together, population centres and rural areas cover all of Canada.

Population centres are classified into three groups, depending on the size of their population:

• small population centres, with a population between 1,000 and 29,999
• medium population centres, with a population between 30,000 and 99,999
• large urban population centres, with a population of 100,000 or more.

Population centre population includes all population living in the cores, secondary cores and fringes of census metropolitan areas (CMAs) and census agglomerations (CAs), as well as the population living in population centres outside CMAs and CAs.

Reported in

2021, 2016 and 2011

Remarks

A review of the population centre concept was undertaken in 2012. The purpose of this review was to determine if the delineation rules that had been maintained over the years could be updated to optimize population centre boundaries. Based on the review, population centres were redelineated using a revised set of criteria for the 2016 Census. This rebase allowed the addition of new delineation thresholds, the inclusion of new data sets, and removal of certain constraints limiting spatial overlap with other administrative geographies.

Table 1.7 indicates how each of the three groups of population centres have changed since 2016.

The 2021 delineation rules for population centres (POPCTR) are ranked in order of priority:

1. The 2016 population centres were retained as 2021 population centres if their current census population remained at 1,000 or more and they maintained a population density of at least 400 persons per square kilometre.
2. If a dissemination block has a population density of at least 200 persons per square kilometre or an employment density of 400 employees per square kilometre and it is adjacent to a population centre, then it is added to the population centre.
3. If a dissemination block or group of contiguous dissemination blocks has a population density of at least 400 persons per square kilometre for the current census, then the DB or group of contiguous DBs is delineated as a population cluster.
4. If a dissemination block has a population density of at least 200 persons per square kilometre or an employment density of 400 employees per square kilometre and is adjacent to a population cluster, then it is added to that cluster.
5. In order to be retained as a population centre, the resulting population cluster must have a minimum population of 1,000 and a population density of at least 400 persons per square kilometre.
6. The distance by road between population centres is measured. If the distance is less than two kilometres, then the population centres are, in most cases, combined to form a single population centre. Certain restrictions apply when combining population centres located less than two kilometres apart. For example, population centres are only combined if they do not cross census metropolitan area or census agglomeration boundaries, or if the population centre, which is also a secondary core, is not combined with another core. In some instances, population centres are not combined because the current block structure does not always permit such a merger. For example, if the addition of intermediate blocks would cause the population density of the newly formed population centre to drop below 400 persons per square kilometre, then the blocks would not be added and the two near‑adjacent population centres would remain separated.
7. Dissemination blocks that correspond to airport locations and are less than two kilometres away from the nearest population centre are added to that population centre, provided that they do not compromise the population density threshold of 400 persons per square kilometre.
8. Interior holes are filled, and irregularities to outer boundaries are smoothed.

The resulting population centres are reviewed and may be modified to ensure spatial contiguity and optimal boundaries.

Most population centres contain commercial and industrial districts, railway yards, airports, parks and other uninhabited areas that result in the inclusion of dissemination blocks with population densities of less than 400 persons per square kilometre. The inclusion of less populated areas can be explained in part by the use of employment density and airport data. In general, the impact on the total population within population centres is minor, but the impact on specific land areas could be significant.

Once a population centre attains a population of 10,000 persons, it is eligible to become the core of a census agglomeration (CA). Once a population centre attains a population of 50,000 and is the core of a CA with a minimum total population of 100,000, then it is eligible to become the core of a census metropolitan area (CMA). When a population centre with a population of at least 50,000 persons is also the core of a CA, the CA is eligible for the census tract program.

Naming convention

The name of the population centre is the name of the principal census subdivision (CSD) when the CSD is (or was) a city, town or village. If two or more principal CSDs are involved, the population centre may be given a compound name. In other cases, the name of the population centre is an appropriate place name. If two previous census population centres are amalgamated, the previous census names are considered for a compound name.

In order to maintain historical comparability, an effort is made to keep core and secondary core names unchanged between censuses. For the 2021 Census Bowmanville has been renamed back to Bowmanville – Newcastle due to the merger of the two population centres.

Geographic code

Population centre codes are unique four‑digit codes that are assigned sequentially upon the POPCTR creation. These codes remain constant between censuses. If a population centre is retired due to amalgamation or failure to meet the current census population or density thresholds, then its code is retired. If a population centre is added, it is assigned the next available POPCTR code.

It is recommended that the two‑digit province/territory (PR) code precede the POPCTR code in order to identify each POPCTR uniquely within its corresponding province/territory. For example:

Four POPCTRs straddle provincial boundaries: Hawkesbury (Ontario and Quebec), Ottawa – Gatineau (Ontario and Quebec), Flin Flon (Manitoba and Saskatchewan) and Lloydminster (Alberta and Saskatchewan).

Table 1.1 shows the number of population centres by province and territory.

Refer to the related definitions of Census Metropolitan Area (CMA) and Census Agglomeration (CA); Census Subdivision (CSD); Core, Fringe and Rural Area; Designated Place (DPL); Dissemination Block (DB); Land Area; Place Name (PN) and Population Density.

Changes prior to the current census

For 2016, the population centres were redelineated using a revised set of criteria. To begin the rebasing of population centres, the first rule, which stated that previous census population centres had to be retained if their population was 1,000 or more, was removed. Instead of retaining the previous census (2011) population centres and using them as a starting point, current census (2016) dissemination blocks were used as building blocks for the delineation. In addition, new thresholds were added to the delineation steps.

The population density of 400 persons per square kilometre was retained as the primary density threshold, and a secondary population density threshold of 200 persons per square kilometre was added. Employment density was also added to the delineation. Employment density was calculated for each dissemination block based on data obtained from Statistics Canada's Business Register, and a threshold of 400 employees per square kilometre was chosen for the delineation.

The 2016 delineation rules for population centres are ranked in order of priority:

1. If a dissemination block or group of contiguous dissemination blocks, each has a population density of at least 400 persons per square kilometre for the current census, then the DB or group of contiguous DBs is delineated as a population cluster.
2. If a dissemination block has a population density of at least 200 persons per square kilometre or an employment density of 400 employees per square kilometre and is adjacent to a population cluster, then it is added to that cluster.
3. In order to be retained as a population centre, the resulting population cluster must have a minimum population of 1,000 and a population density of at least 400 persons per square kilometre.
4. The distance by road between population centres is measured. If the distance is less than two kilometres, then the population centres are, in most cases, combined to form a single population centre. Certain restrictions apply when combining population centres located less than two kilometres apart. For example, population centres are only combined if they do not cross census metropolitan area or census agglomeration boundaries, or if the population centre, which is also a secondary core, is not combined with another core. In some instances, population centres are not combined because the current block structure does not always permit such a merger. For example, if the addition of intermediate blocks would cause the population density of the newly formed population centre to drop below 400 persons per square kilometre, then the blocks would not be added and the two near‑adjacent population centres would remain separated.
5. Dissemination blocks that correspond to airport locations and are less than two kilometres away from the nearest population centre are added to that population centre, provided that they do not compromise the population density threshold of 400 persons per square kilometre.
6. Interior holes are filled, and irregularities to outer boundaries are smoothed.

The resulting population centres are reviewed and may be modified to ensure spatial contiguity and optimal boundaries.

New for 2016, population centre, designated place and census subdivision overlap is permitted.

Two core names were updated between 2011 and 2016 as a direct result of the spatial representation of the rebased population centres.

Bowmanville – Newcastle was renamed to Bowmanville

St. Catharines – Niagara was renamed to St. Catharines – Niagara Falls

For the 2011 Census, the term 'population centre' replaced the term 'urban area.' The term 'urban area' existed at Statistics Canada from the 1961 to 2006 censuses.

Prior to 2011, urban areas included a wide range of densely‑populated areas, from small centres with a population of 1,000 to very large centres of more than 1 million. This approach ignored size differences by treating all urban areas as a single group. Given the widely accepted view that a more dynamic urban‑rural continuum exists, the use of the term 'urban area' could lead to misinterpretations.

In 2011, population centres were divided into three groups for the first time based on the size of their population to reflect the existence of an urban-rural continuum.

The 2011 delineation rules for population centres (POPCTR), ranked in order of priority, were as follows:

1. The 2006 urban areas were retained as 2011 population centres if their current census population remained at 1,000 or more.
2. If a dissemination block with a population density of at least 400 persons per square kilometre was adjacent to a population centre, then it was added to that population centre.
3. If a dissemination block or group of contiguous dissemination blocks, having a minimum population of 1,000 and a population density of at least 400 persons per square kilometre for the current census, then the dissemination block or group of contiguous dissemination blocks was delineated as a new population centre.
4. The distance by road between population centres was measured. If the distance was less than two kilometres, then the population centres were combined to form a single population centre, provided they did not cross census metropolitan area (CMA) or census agglomeration (CA) boundaries.
5. If a population centre was contained within a census subdivision (CSD) or a designated place (DPL), the difference in land area between the population centre and the CSD or DPL was calculated. For confidentiality purposes, if the difference between the CSD and the population centre was less than 10 square kilometres, then the boundary for the population centre was adjusted to match the CSD boundary. However, if the difference between the DPL and the population centre was less than 10 square kilometres and the remaining population was less than 100, then the population centre annexed the entire DPL and the DPL was retired.

Previous to the 2016 Census, DPLs could not overlap POPCTR boundaries, with one exception permitted in 2011. The DPL of Cowichan 1 (DPL 59 0321) in British Columbia overlapped the POPCTR of Duncan (POPCTR 0243). In an effort to minimize data suppression for this area, this DPL represented a formerly discontiguous Aboriginal community which had been combined to form a single discontiguous census subdivision (CSD).

For 2006, the boundaries of 412 urban areas for 2001 were adjusted to correct for over-bounding which largely resulted from the 2001 block structure. This correction resulted in the reduction of land area of these 2001 urban areas in preparation for the delineation of the 2006 urban areas. The correction also resulted in the reinstatement of four urban areas for 2006 which had been merged with other urban areas in 2001: Fortune (10 0300), Sainte‑Croix (24 0878), Châteauguay (24 1177) and Dowling (35 1084).

One of the 2006 urban areas, Attawaspiskat 91A (UA 35 1275), was an area that had been identified as being an incompletely enumerated Indian reserve. Data for 2006 were not available for the incompletely enumerated reserves and settlements, and were not included in tabulations. Because of the missing data, users were cautioned that for the affected geographic areas, comparisons (e.g., percentage change) between 2001 and 2006 were not exact.

In 2001, the delineation of urban areas became an automated process that made it possible to use population counts and population density data from the current census.

Prior to 2001, the geographic units used for urban area delineation were census subdivisions, designated places and enumeration areas. Population counts and population density from the previous census were used in all cases, except when enumeration area boundaries had been adjusted for the current census.

For 1976, urban areas contained a population concentration of at least 1,000 persons and a population density of at least 1,000 persons per square mile (386 per square kilometre). Urban areas were combined if they were separated by less than one mile (1.6 kilometres).

For 1971, 1966 and 1961, urban areas included:

• all incorporated cities, towns and villages with a population of 1,000 persons or over;
• all unincorporated places with a population of 1,000 persons or over and a population density of at least 1,000 persons per square mile; and
• the urbanized fringe and the urbanized core of a census agglomeration or census metropolitan area, that had a minimum population of 1,000 persons and a density of at least 1,000 persons per square mile.