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Census Geography

Introduction

The planning of a census begins several years before the actual Census Day. Before data collection can take place, geographic boundaries delineating
enumeration areas (EAs) must be drawn across the country. A census representative (CR) is responsible for the enumeration of each EA. More than 44,000 maps must be generated from information provided by provincial authorities and planning boards before collection can begin. Once collection and processing have been completed, data are disseminated for geographic levels ranging from Canada-wide totals to individual communities. Between collection and dissemination, geographic coding occurs in a wide range of census operations. Hence, defining Canada's geographies for the purpose of conducting a census becomes an integral part of the process as it forms the basis from which our government takes shape and from which data about Canadians can be captured, monitored and analysed.

Statistics Canada uses a very accurate and detailed geographic structure that makes it possible to obtain information for many different geographical units, known as geographic areas. Data from the 1991 Census are available for numerous standard geographic areas, as well as for non-standard or user-defined areas. Standard areas are of two types:

(a) Legislative/administrative areas are defined, with a few exceptions, by Canadian federal and provincial statutes. These include:

(b) Statistical areas are defined by Statistics Canada as part of the spatial frame used to collect and disseminate census data. These include:

User-defined Areas

Census data can also be produced for areas other than the standard geographic areas, that is, for user-defined areas. These are of two types: aggregation of standard geographic areas and custom query areas. The latter are created by aggregating small building-block geographical units: block-faces in large urban areas (generated from machine-readable street maps called Street Network Files) and enumeration areas elsewhere. A co-ordinate (representative point) is assigned to every enumeration area in Canada and to each block-face in most of the large urban areas (50,000 population and over). With the geocoding system, households and the associated data are geographically coded or "geocoded" to the block-face representative points within each area.

The main difference between the two is that the administrative regions are areas defined by other authorities and are adopted for purposes of the census whereas the statistical areas are defined by Statistics Canada for the purposes of producing census data and of complementing the structure of administrative regions. The main links between the two types of geographic areas are examined in Subsection 1.3 .

The enumeration area is the smallest unit and the building block underlying all other standard geographic areas. For example, the 45,995 EAs can be aggregated into 295 federal electoral districts or into 6,006 census subdivisions.

1.2 Changes from the 1986 Census

The geographic concepts used for the 1991 Census have not changed significantly since the 1986 Census. Nevertheless, the coverage of some geographic areas has been modified to reflect population change and distribution. For example, some urban areas and census agglomerations have been deleted and two new census agglomerations (Red Deer, Alta., and Matsqui, B.C.) have been added to the census tract program. At the same time, legislative changes have affected the coverage of other geographic areas. For example, the 1991 Census of Canada has been taken according to the 295 federal electoral districts defined by the 1987 Representation Order, while census divisions in Quebec have been redefined. Census subdivisions (or municipalities) are subject to change (names, boundaries, status) from one census to the next. For additional information, refer to the 1991 Census Dictionary (Statistics Canada, Catalogue No. 92-301 E or D).

As well, two new types of geographic regions have been added to the hierarchy of standard administrative areas: the subprovincial region and the agricultural region.

1.3 Overview of the Standard Geographic Areas

The following standard geographic areas are used in the dissemination of census data:
Geographic areaTotal number
Enumeration areas (EAs)45,995
Census tracts (CTs)4,068
Provincial census tracts (PCTs)1,815
Urban areas/rural areas893
CMA/CA partsN/A
Primary census metropolitan areas (PCMAs)12
Primary census agglomerations (PCAs)21
Census metropolitan areas (CMAs)25
and census agglomerations (CAs)115
Federal electoral districts (FEDs)295
Census subdivisions (CSDs)6,006
Census consolidated subdivisions (CCSs)2,630
Census divisions (CDs)290
Agricultural regions76
Subprovincial regions (SPRs)68
Provinces/territories12

Definitions, historical boundary changes and descriptions of available maps are covered more thoroughly in the other census reference products, including the 1991 Census Dictionary (Statistics Canada, Catalogue No. 92-301 E or D), the 1991 Census Catalogue (Statistics Canada, Catalogue No. 92-302 E) and the 1991 Census Geography: A Historical Comparison (Catalogue No. 93-311 E).

1.3.1 Enumeration area (EA) [Return to List of Statistical Areas]

An enumeration area is the area canvassed by one census representative. It is the basic building block of all standard geographic areas. EAs are defined by the number of households they contain and by physical boundaries such as bodies of water and streets. An EA never cuts across any boundary recognized by the census. The enumeration area is normally the smallest geographical unit for which census data are available. Therefore, it is defined in accordance with the following criteria:
(a) Dwellings: the number of dwellings in an EA may vary from 375 (maximum) in large urban areas to 125 (minimum) in rural areas.
(b) Limits: since the EA is the basic unit for all geographic areas, it must never overlap an area recognized by the census (federal electoral districts, census divisions, census subdivisions, census tracts, etc.) Moreover, the borders are defined in such a way that the Census Representative can locate them without difficulty (for example, using streets, roads, railways and rivers).
The EAs are primarily census collection units; they are not designed as dissemination areas. For reasons of confidentiality, only some information is available.

1.3.2 Census tract (CT)

A census tract is a small census geographic area established in a large urban community withthe assistance of local specialists who help define boundaries that are useful for urban and social research. These boundaries are rarely altered; however, they do change when census Subdivision (CSD) boundaries change or when CT splits occur in areas of rapid growth. In cases where CTs are split, both parts are labelled with a numerical identifier to allow for comparative studies between identical CT boundaries of previous censuses. Populations of CTs vary between 2,500 and 8,000 persons, with an average of about 4,000. For the 1991Census, 39 census metropolitan areas (CMAS) and census agglomerations (CAs) have census tracts.

All CMAs and CAs containing a CSD with a population of 50,000 or more at the previous census are eligible for a census tract program. For example, the central area of the Sherbrooke CMA is divided into CTs. Once an urban centre is added to the program, it is retained even if its population subsequently declines.

An example of the kind of social research done using census tract boundaries is "Changes in Mortality by Income in Urban Canada from 1971 to 1986". The findings of this study were a joint effort undertaken by the Policy, Planning and Information Branch, Health and Welfare Canada, and the Canadian Centre for Health Information, Statistics Canada. In this study, postal codes were matched to census data for particular census tracts by using the Postal Code Conversion File (PCCF). The purpose of such a study is to enable communities to analyse community health, prepare plans for the future and monitor and evaluate local health programs.

1.3.3 Provincial census tract (PCT)

A provincial census tract is a permanent small rural or urban census geographic area. It exists in areas not covered by the census tract program. Populations of PCTs vary between 3,000 and 8,000 persons, with an average of about 5,000. As much as possible, their limits follow permanent physical features or geographic boundaries suggested by authorities of the provinces and territories.

1.3.4 Urban area/rural area

An urban area is a continuously built-up area with a population of 1,000 or more and a population density of at least 400 persons per square kilometre based on the previous census. To be considered continuous, the built-up area must not have a discontinuity exceeding two kilometres. A rural area is defined as any area that does not meet the requirements for an urban area.

1.3.5 CMA/CA parts

CMA/CA parts are the rural and urban areas within a census metropolitan area (CMA) or a census agglomeration (CA). There are three CMA/CA parts:

(a) urbanized core: a large urban area around which a CMA or CA is delineated;

(b) urban fringe: an urban area within a CMA or CA, but outside of the urbanized core;

(c) rural fringe: all territory within a CMA or CA lying outside of urban areas.

Every CMA, CA, PCMA and PCA has an urbanized core, but may or may not have urban or rural fringe areas. The total urbanized core of a consolidated CMA or CA is the sum of the constituent cores. Similarly, the totals for urban and rural fringes of a consolidated CMA or CA are the sums of the constituent fringes.

1.3.6 Primary census metropolitan area (PCMA) and primary census (PCA) agglomeration

In some regions, a neighbouring census metropolitan area (CMA) and census agglomeration (CA) are sometimes economically and socially linked. In this case, they are grouped together to form a single CMA and CA (consolidated).

This consolidated CMA is divided into a primary census metropolitan area (PCMA) and one or more primary census agglomerations (PCAs). Thus, a PCMA or a PCA is a labour market subregion within the larger consolidated CMA or CA. All PCMAs or PCAs, like regular CMAs contain one or more census subdivisions.

1.3.7 Census metropolitan area (CMA) and census agglomeration (CA)

Urban structure and economic links between cities are such that, in many cases, the data dealing with a particular city (a census subdivision) do not take into account that city's true area of influence. This, for example, is what happens in the case of the cities of Toronto, Ottawa-Hull, Montreal, Quebec, Chicoutimi and Windsor, where bedroom communities play a vital economic role with respect to the census subdivision (CSD). A CMA is an urbanized core of at l east 100,000 population (based on the previous census), together with its main labour market area.

A CA is the main labour market area of an urbanized core with a population of at least 10,000 based on the previous census. The 1991 Census recognizes 25 CMAs and 115 CAs.

Once a CA attains an urbanized core population of 100,000, it becomes a CMA and continues to be one even if its population subsequently declines below 100,000. However, if the population of a CA in an urbanized core drops below 10,000, the CA is removed from the CA program.

The 1991 CMAs and CAs were delineated using data derived from the place of work and place of residence questions in the 1981 Census (see Section 5 of this chapter for a description of these two questions). For a census subdivision (CSD) to be included in a CMA, at least one of the following criteria must be satisfied:

the CSD falls completely or partly inside the urbanized core;

at least 50% of the employed labour force living in the CSD works in the urbanized core;

at least 25% of the employed labour force working in the CSD lives in the urbanized core;

if a CSD meets the criteria for inclusion, but is not contiguous to a CMA, the place of work commuting flow data are aggregated for all CSDs within the census consolidated subdivision (CCS) - inclusion or exclusion of the entire CCS within a CMA is then determined;

if the commuting flow is less than 100 persons, CSDs are excluded from the CMA, even if the second or third criteria apply;

even if the second, third, fourth or fifth criteria apply, CSDs may be included or excluded to maintain the contiguity of the CMA.

Adjacent CMAs and CAs which are socially and economically integrated are grouped to form a single consolidated CMA or CA. Regular CMAs and CAs, on the other hand, are independent. For such areas to be eligible for consolidation, the total commuting interchange between the particular CMAs and CAs must be equal to at least 35% of the labour force living in the smaller CMA or CA. If consolidation takes place, the original CMAs or CAs become subregions (called primary CMAs or CAs) within the consolidated CMA or CA.

The implications for residents occupying areas subject to consolidation could include, for instance, additional taxes to support metropolitan services. Increased taxes in support of city public transportation systems is an example of the possible effects of consolidation. On the other hand, the residents of such areas could be eligible to apply for special programs and benefits.

1.3.8 Federal electoral district (FED)

Federal electoral districts are established by the Parliament of Canada. Each FED is represented by a member in the House of Commons. When the electoral map is revised, Statistics Canada readjusts the data so that they correspond to the new district boundaries, There are 295 FEDs in Canada according to the 1987 Representation Order.

FEDs are defined according to the following criteria:

. the legal limits and descriptions are the responsibility of the Chief Electoral Officer and are published in the Canada Gazette;

. FED limits are usually revised every I 0 years after the results of the decennial census

1.3.9 Census subdivision (CSD)

Census subdivisions are municipalities, Indian reserves, Indian settlements andunorganized territories. Unorganized territories usually cover remote regions, where there are no legally defined municipalities covering the entire territory. Every city, town and village, for example, is a census subdivision. There are 6,006 census subdivisions in Canada. In Newfoundland, Nova Scotia and British Columbia, CSDs can also be geographic areas created by Statistics Canada, in co-operation with the provinces, as equivalents for municipalities.

1.3.10 Census consolidated subdivision (CCS)

The concept of a CCS is a grouping of small census subdivisions within a containing censussubdivision (CSD), created for the convenience and ease of geographic referencing. CCSs are used primarily in the dissemination of the census of agriculture data. They may have changed since the last census if the component CSDs have changed. For 1991, several CCSs have been modified in the province of Quebec following the implementation of the new census division structure in that province.

Census consolidated subdivisions are delineated according to these rules:

*all CSDs smaller than 25 square kilometres are grouped with a larger CSD;

*a CSD larger than 25 square kilometres forms a CCS of its own unless it is surrounded on more than half its perimeter by another CSD; then it is included as part of the CCS formed by the other CSD;

*a CSD with a population greater than 100,000 persons forms a CCS on its own if it is surrounded by rural CSDs;

*the CCS name usually coincides with its largest CSD components in terms of land area.

1.3.11 Census division (CD)

"Census division" is the general term used for counties, regional districts, regional municipalities and five other types of geographic areas made up of groups of census subdivisions. There are 290 CDs in Canada.

There has been a complete restructuring of census divisions in Quebec between 1986 and 1991. CDs in Quebec will now respect the same legal limits as the municipalites regionales de comtes (MRCs) or their equivalents (e.g. "communautes urbaines" and territoires conventionnes"). The implementation of MRCs (or their equivalents) has led to an increase in the number of CDs in Quebec, from 76 in 1986 to 99 in 1991.

In Ontario, the CDs correspond to the counties, districts, district municipalities, metropolitan municipalities, regional municipalities and united counties.

Before we had postal codes, counties were used for identification purposes when sending by mail. They have been retained for the census so that data obtained over the years may be compared.

1.3.12 Agricultural region

An agricultural region is a subprovincial geographic region used by the census of agriculture in the dissemination of agricultural statistics. In all provinces except Prince Edward Island and Saskatchewan, an agricultural region is a contiguous group of census divisions. In Saskatchewan, agricultural regions are groupings of census consolidated subdivisions, but these groupings do not necessarily respect census division boundaries. For Prince Edward Island, Yukon and Northwest Territories, agricultural regions have not been defined.

1.3.13 Subprovincial region (SPR)

A subprovincial region refers to the geographical unit smaller than a province (with the exception of P.E.I. and the territories) made up of groupings of census divisions. The SPRs were created in response to the requirement for a geographical unit suitable for analysis of regional economic activity. Such a unit is small enough to permit regional analysis, yet large enough to include a sufficient number of respondents such that, after confidential data are suppressed, a broad range of statistics can be released.

1.3.14 Province/territory

The ten provinces and the two territories are the major political units of Canada. They are also the basic geographic units for tabulating and cross-classifying census data.