The Main Structure of the ASGC is used to collect and disseminate a broad range of ABS social, demographic and economic statistics. Although the Main Structure is the most widely used and has broad application, the other structures are equally important to their own purposes. Maps depicting the Main Structure boundaries are provided in Maps.
The Main Structure has five hierarchical levels at Population Census times, comprising in ascending order: CDs-SLAs-SSDs-SDs-S/Ts. In non-census years, CDs are undefined and the Main Structure thus has only four levels of hierarchy.
In this structure, CDs aggregate to form SLAs, SLAs aggregate to form SSDs and this aggregation principle continues up the remaining hierarchical levels. At each hierarchical level, the component spatial units (e.g. SLAs) collectively cover all of Australia without gaps or overlaps.
(showing three hierarchical levels: S/T-SD-SSD)
Detailed tables of the Main Structure are shown in The Classification Structures.
(showing four hierarchical levels: S/T-SD-SSD-SLA)
- Main Structure - Detailed
THE SPATIAL UNITS
Census Collection District (CD)
CDs are designed for use in census years for the collection and dissemination of Population Census data. In non-census years, CDs are undefined. In aggregate, CDs cover the whole of Australia (as defined in Chapter 1, p. 5) without gaps or overlaps.
The CD is the smallest spatial unit in the ASGC. CDs aggregate to form the larger spatial units of SLAs in the Main, Statistical Region, Statistical District and LGA Structures, Sections of State in the SOS Structure, Urban Centres and Localities in the UC/L Structure and Remoteness Areas in the Remoteness Structure. Aggregation of SLAs in turn forms the remaining spatial units in the ASGC. Therefore, in census years, the CD is the common denominator which integrates all classification structures in the ASGC (see ASGC Structural Chart, Chapter 1, p. 4).
The traditional concept of a CD is that it defines an area that one census collector can cover, delivering and collecting census forms, in about a ten-day period. However, in the interests of comparability between censuses, this criterion is no longer strictly observed. In the 2001 edition, many urban CDs were of a size such that census collectors may have been allocated more than one CD. In urban areas CDs average about 220 dwellings. In rural areas the number of dwellings per CD reduces as population densities decrease. By design, CD boundaries do not cross SLA (and thus LGA) boundaries. Therefore, an aggregation of CDs covers the administrative area of a local government.
For the 2001 Census, 37,209 CDs were defined throughout Australia.
Delimitation of CDs
For the 2001 Census, the following criteria were used for delimiting CDs:
Special purpose CDs
Special purpose CDs are created so that special enumeration procedures can be applied. They include:
- CDs should be consistent with the requirements of a collector’s workload and be a useful spatial unit providing the building blocks capable of aggregation into broader level ASGC spatial units.
- The area and population delimited by a CD boundary must not be so great that one collector cannot deliver and collect census forms within about ten days.
- The chosen CD boundaries should, if possible, be readily identifiable on the ground, be defined in terms of permanent features, follow the centre of a road or river if these features are used and should delimit CDs which conform to existing and proposed land uses. The use of major roads as CD boundaries in rural areas should be avoided where possible, i.e. to minimise splitting of identifiable rural localities.
- CDs should conform where possible to existing/gazetted suburb boundaries. CDs must not cross SLA boundaries and, as a consequence, any other ASGC spatial unit boundary.
- CDs should not be designed in such a way as to make them confidential for publication of data. Accordingly, a CD should contain, where possible, at least 100 persons at the next census. For dissemination purposes, Indigenous Community CDs will have a limit of 80 persons.
- CDs in aggregate must cover the whole of Australia (as defined in Chapter 1, p. 5) without gaps or overlaps.
A number of these special purpose CDs have no actual boundary. They are represented as points instead of areas on maps.
- Indigenous Community CDs
- Defence Establishments CDs
- Mining or Construction towns or camps CDs
- Major Waterways CDs
- Nil CDs.
Indigenous Community CDs are defined where there is a significant Indigenous population.
Defence Establishments CDs are defined where there is a clear boundary and special enumeration procedures are required.
Mining or Construction CDs are defined when the town or camp is expected to exist for at least two censuses.
Major Waterways CDs consist of water only and contain no population. They are mostly found in urban areas where an LGA boundary extends from the shore to include part of a body of water.
Nil CDs are created for areas where it is not expected that persons or dwellings will be enumerated. This may be an expanse of National Park which, if included in an adjoining populated area would provide a distorted view of population density for that area.
Off-shore, shipping and migratory CDs
Off-shore, shipping and migratory CDs are not spatial units in the usual sense - they have no defined boundaries. They are designed to facilitate the recording of people on census night who are off-shore on oil rigs, drilling platforms and other structures; on board vessels in and between Australian ports; or are in transit on board long distance trains, buses and aircraft.
Off-shore, shipping and migratory CDs are not defined for the Australian Capital Territory and the Other Territories. For the 2001 Census, Australian residents temporarily in Antarctica, Heard or Macquarie Islands, were included in the off-shore, shipping and migratory CDs of Tasmania.
CDs are identified by unique six-digit codes within each S/T.
Statistical Local Area (SLA)
The SLA is a general purpose spatial unit. It is the base spatial unit used to collect and disseminate statistics other than those collected from the Population Censuses. In non-census years, the SLA is the smallest unit defined in the ASGC. In census years, an SLA consists of one or more whole CDs. In aggregate, SLAs cover the whole of Australia (as defined in Chapter 1, p. 5) without gaps or overlaps.
1160501 is CD 160501 of New South Wales
5051901 is CD 051901 of Western Australia
SLAs aggregate directly to form the larger spatial units of SSDs in the Main Structure, SRSs in the SR Structure and LGAs in the LGA Structure (see ASGC Structural Chart, Chapter 1, p. 4). SSDs in turn aggregate to form the larger spatial units of S Dists in the S Dist. Structure. Therefore, the SLA is the common denominator which integrates the four classification structures in use in both census and non-census years.
In this edition of the ASGC, there are 1,415 SLAs in Australia including one SLA for each of the three Territories of Jervis Bay, Christmas Island and Cocos (Keeling) Islands.
SLAs are listed in the table - Local Government Areas and Statistical Local Areas - Alphabetic - in The Classification Structures.
Delimitation of SLAs
SLAs are based on the boundaries of incorporated bodies of local government where these exist. These bodies are the Local Government Councils and the geographical areas which they administer are known as Local Government Areas (LGAs).
An LGA is an SLA if it fits entirely within an SSD and is broadly similar in size, economic significance and user needs for statistics to other LGAs in Australia.
For example, the SLA Albury (C) corresponds to the whole LGA of City of Albury in New South Wales. In this edition of the ASGC, 488 of the total 1,415 SLAs, approximately 34%, equate with a whole LGA while approximately 73% of the 667 LGAs equate with one SLA.
An LGA will be composed of two or more SLAs when the above conditions are not met. This can occur if an LGA is divided by the boundary of one or more SSDs or where the LGA is substantially different in size, economic significance and user needs for statistics to other LGAs. The LGA is then split into two or more SLAs which generally correspond to one or more suburbs (as occurs in the predominantly urban LGA of the City of Brisbane) or other areas of interest.
For example, the LGA of Shire of Calliope in Queensland is split into two SLAs Calliope (S) - Pt A and Calliope (S) - Pt B because it is split by an SSD boundary, and, the LGA of the City of Brisbane is split into 158 SLAs generally based on suburbs.
There are large parts of Australia which are not administered by incorporated local government bodies. For those areas an SLA is an unincorporated area. Unincorporated SLAs are defined for unincorporated on-shore area(s) and/or off-shore island(s) in an SSD or are defined for that part of an unincorporated area which is considered of sufficient economic significance as to warrant the formation of a separate SLA.
For example, Unincorp. Pirie is an unincorporated SLA in the Pirie SSD in South Australia and Unincorp. Islands is an unincorporated SLA in North West SSD in Queensland. Similarly the SLAs of Petermann and Tanami in Central NT SSD in the Northern Territory are unincorporated areas.
Other large parts of Australia which are unincorporated include the unincorporated part of the Northern Territory. For the SSD Daly the entire area is covered by one unincorporated SLA. In other SSDs (e.g. East Arnhem), the unincorporated area is split into several SLAs to distinguish an economically significant town (e.g. Nhulunbuy), island (e.g. Groote Eylandt) or administrative region. The Australian Capital Territory is entirely an unincorporated area where each SLA is either a suburb, a locality or the non-urban area of an SSD.
Off-Shore Areas & Migratory SLAs, formed for census purposes for all S/Ts except the Australian Capital Territory and Other Territories to encompass off-shore, shipping and migratory CDs (off-shore, shipping and migratory CDs are explained in Chapter 2, p. 9)
The naming conventions for SLAs are as follows:
For example, the LGA of Stirling (C) in Western Australia is split into three SLAs:
- An SLA which is a whole LGA adopts the name of the LGA including its LGA status as a suffix. Thus, Northam (S) and Northam (T) in Western Australia are separate SLAs. The various LGA types currently in use by states and the Northern Territory are specified in Chapter 3, p. 20.
- An SLA which is part of an LGA may adopt a hyphenated name the first part of which is the name of the LGA.
For example, the LGA of the Municipality of Latrobe in Tasmania is split into two SLAs:
Stirling (C) - Central
Stirling (C) - Coastal
Stirling (C) - South-Eastern
- If the name includes - Pt A, - Pt B, or - Pt C, this indicates the SLAs were formed by splitting an LGA between two or more SSDs and - Pt A usually denotes the more urban part of the split LGA.
For example, the LGA of the City of Brisbane in Queensland is split into 158 SLAs, including:
Latrobe (M) - Pt A
Latrobe (M) - Pt B
- An SLA which is part of an LGA may adopt a locality or suburb name.
For example, the SLAs West Arnhem (in Northern Territory) Bruce (in Australian Capital Territory) and Unincorp. Far West (in New South Wales).
- The name of an SLA which covers an unincorporated area does not contain LGA type. In New South Wales, Queensland and South Australia the SLA name may include Unincorp.
- A small number of SLA names are duplicated across S/Ts and one SLA name is duplicated within an S/T. These names become unique when used in conjunction with SLA codes.
City (Queensland and Australian Capital Territory)
City - Inner (Queensland and Northern Territory)
City - Remainder (Queensland and Northern Territory)
Durack (Queensland and Northern Territory)
Kingston (Queensland and Australian Capital Territory)
Oxley (Queensland and Australian Capital Territory)
Red Hill (Queensland and Australian Capital Territory)
West End (Townsville (C) and Brisbane (C))
The coding conventions for SLAs are as follows:
- SLAs are identified by four-digit codes. These codes are unique only within an S/T. For unique Australia-wide identification the four-digit SLA code must be preceded by the unique one-digit S/T code.
Barcaldine (S) 0400 (in Queensland) (S/T code 3)
Arltarlpilta (CGC) 0400 (in Northern Territory) (S/T code 7)
- The fourth (last) digit of the SLA code indicates the following:
- 0 means the SLA is a whole LGA.
Ashburton (S) 0250 (in Western Australia)
- 1-8 means the SLA is part of an LGA.
Sorell (M) - Pt A 4811 (in Tasmania)
Sorell (M) - Pt B 4812 (in Tasmania)
- 9 means the SLA is either an unincorporated area, an Off-Shore Areas & Migratory SLA or an undefined category (see Chapter 3, p. 20; Chapter 2, p. 10 or Chapter 9, p. 43, respectively).
Statistical Subdivision (SSD)
The SSD is a general purpose spatial unit of intermediate size between the SLA (smaller) and the SD (larger) in the Main Structure.
Bruce 0729 (in Australian Capital Territory)
Off-Shore Areas & Migratory 9779
- Within each S/T, SLA codes are in the range of 0001-9990; codes ending with 99 and those within the range of 9991-9999 have been reserved for special purposes Special Purpose ASGC Codes.
- In the Main Structure, SLA codes are arranged in ascending numerical order within an SSD. Gaps have been provided between the codes for future expansion or change.
In this edition of the ASGC, there are 207 SSDs in Australia.
- SSDs consist of one or more SLAs. In aggregate, they cover Australia (as defined in Chapter 1, p. 5) without gaps or overlaps. The larger spatial units of SDs and S Dists can be formed by aggregation of SSDs (see ASGC Structural Chart, Chapter 1, p. 4). SSDs do not cross S/T boundaries except in the case of the Other Territories SSD, which comprises the three Territories of Jervis Bay, Christmas Island and Cocos (Keeling) Islands.
Delimitation of SSDs
The delimitation criteria for SSDs are as follows:
For example, the Ballarat City SSD in Victoria covers the same area as the Ballarat S Dist.
- SSDs are defined as socially and economically homogeneous regions characterised by identifiable links between the inhabitants. Moreover, in the non-urban areas (i.e. outside the capital cities or areas with population clusters of 25,000 or more people), an SSD is characterised by identifiable links between the economic units within the region, under the unifying influence of one or more major towns or cities.
- Where possible, SSD boundaries embrace contiguous whole LGAs. However, in some cases e.g. where S Dists or capital city SDs have been defined, an SSD boundary may split the LGA into parts with each part of the LGA forming part of the relevant SSD. For example, the SSDs of Gold Coast City Part A and Gold Coast City Part B dissect the LGA of the City of Gold Coast in Queensland.
- One or more SSDs must be defined for an S Dist. that falls within an S/T.
For example, the Albury SSD in New South Wales plus the Wodonga SSD in Victoria together cover the same area as the Albury-Wodonga S Dist. which lies partly in New South Wales and partly in Victoria.
- One or more SSDs must be defined for each part of an S Dist. which straddles an S/T boundary.
For example, in New South Wales, the SSD of Hunter SD Bal is defined as the part of the Hunter SD which is outside the Newcastle S Dist. (and Newcastle SSD).
- Where an SD contains an S Dist. (or part of an S Dist.), one or more SSDs must be defined for the S Dist. and at least one SSD for the remainder of the SD which falls outside the S Dist. even though the SSD(s) so defined may not have a predominant town or cluster of towns with a unifying socioeconomic influence over the region.
The coding conventions for SSDs are as follows:
- One Off-Shore Areas & Migratory SSD is defined for each S/T except the Australian Capital Territory and Other Territories.
For example, Albury 15505 (in New South Wales) and Wodonga 24505 (in Victoria).
- SSDs are identified by unique two-digit codes within SDs. Unique Australia-wide identification of SSDs is obtained by use of a five-digit code comprising S/T code (digit 1), SD code (digits 2-3) and SSD code (digits 4-5).
Statistical Division (SD)
The SD is a general purpose spatial unit and is the largest and most stable spatial unit within each S/T in the Main Structure.
- SSD code 88 has been reserved for special purposes Special Purpose ASGC Codes.
- In the Main Structure, SSD codes are arranged in ascending numerical order within an SD. Gaps have been provided between the codes for future expansion or change.
SDs consist of one or more SSDs. In aggregate, they cover Australia (as defined in Chapter 1, p. 5) without gaps or overlaps. SDs aggregate to form S/Ts (see ASGC Structural Chart, Chapter 1, p. 4).
In this edition of the ASGC, there are 66 SDs in Australia including one SD for the three Territories of Jervis Bay, Christmas Island and Cocos (Keeling) Islands.
Delimitation of SDs
The current basis for delimiting SDs was determined by the 31st and 33rd Conferences of Statisticians of Australia in 1969 and 1973. The delimitation criteria are as follows:
More specifically, the SDs within the individual S/T have been delimited as follows:
- SDs should ideally be delimited on the basis of socioeconomic criteria and should, where possible, embrace contiguous whole local government areas.
- SD boundaries so delimited should be changed only at infrequent intervals, for example, at periods of 15-20 years.
- SD boundaries should be determined in time for use in the next Population Census if practicable.
- A Capital City SD (currently one in each capital city) should be defined, after consultation with planners, to contain the anticipated development of the city for a period of at least 20 years. This fixed SD boundary - as distinct from the moving urban centre boundary - delimits an area which is stable for general statistical purposes. It represents the city in a wider sense. This delimitation procedure cannot be applied to the separate urban centres within a Capital City SD.
- SDs outside a capital city should be defined as a relatively homogeneous region characterised by identifiable social and economic links between the inhabitants and between the economic units within the region, under the unifying influence of one or more major towns or cities.
SD names tend to indicate their generalised region (e.g. Far North in Queensland). SD names are unique only within an S/T as a small number of SD names are replicated between the states (see example below). SD names become unique when used in conjunction with their SD codes or referenced to their respective state code. One Off-Shore Areas & Migratory SD is defined for each S/T except the Australian Capital Territory and the Other Territories.
- In New South Wales, SDs correspond to proclaimed Government Regions with the exception that North Coast Region consists of the SDs of Richmond-Tweed and Mid-North Coast. These Regions were delimited to maximize the degree of socioeconomic interactions within each Region. Information on transport patterns, telephone traffic between major cities and towns, retail shopping, fresh goods marketing, provincial newspaper circulation areas and coverage of principal radio stations were all used in delimiting these boundaries.
- In Victoria, the SDs prior to 1995 generally corresponded to State Planning Regions adopted by the Victorian Government in October 1981. However, following the restructuring of local government in that State during 1994 and 1995, the SDs were redefined to accord with the general considerations and criteria outlined above.
- In Queensland, formal State Planning Regions have been abolished. SDs are used on an informal basis for State Government planning purposes where relevant. SD delimitation follows the general criteria outlined above.
- In South Australia, State Planning Regions, as proposed by the Committee on Uniform Regional Boundaries for Government Departments (CURB), were adopted by the South Australia Government in 1976. CURB Regions were based on such factors as: population density and distribution, socioeconomic characteristics, political boundaries, government service areas, newspaper circulation, retail trading patterns, etc. Prior to 1998, South Australian SDs did not always correspond to CURB Regions but they always aggregated to these Regions. However, following the restructuring of local government in South Australia in 1996 and 1997, the SDs were redefined to accord with the general considerations and criteria outlined above.
- In Western Australia, State Planning Regions, as proposed by the State Statistical Coordination Committee, were adopted by the Western Australia Government in January 1976. SDs in Western Australia correspond to these Regions. The Perth Metropolitan Region is delimited to be consistent with the overall concepts and planning of Perth and to take into account LGA and CD boundaries. Rural Regions on the other hand are delimited based on the socioeconomic interest of the community; the character of natural resource; the distribution of population and industries; town size; road and railway systems; and production and marketing practices.
- In Tasmania, SD delimitation follows the general considerations and criteria outlined above. They are considered satisfactory for the purpose of State Government planning.
- In the Northern Territory, SDs are based on Territory Government Administrative Regions, and are consistent with the general considerations and criteria for their delimitation described above.
- In the Australian Capital Territory, SD delimitation follows the general considerations and criteria outlined above.
- In the Other Territories, the SD has been delimited to represent the aggregated area of the Territories of Jervis Bay, Christmas Island and Cocos (Keeling) Islands.
The coding conventions for SDs are as follows:
Central West (in New South Wales and Queensland)
Northern (in New South Wales, Queensland, South Australia and Tasmania)
South West (in Queensland and Western Australia)
South Eastern (in New South Wales and Western Australia)
- SDs are identified by unique two-digit codes within an S/T. Unique Australia-wide identification of SDs requires a three-digit code comprising S/T code (digit 1) and SD code (digits 2-3).
State and Territory (S/T)
The S/T is the largest spatial unit in the Main Structure and in the ASGC.
- The SD code 85 is reserved for Off-Shore Areas & Migratory SDs and the SD code 88 has been reserved for special purposes Special Purpose ASGC Codes.
- In the Main Structure, SD codes are arranged in ascending numerical order within an S/T. Gaps have been provided between the codes for future expansion or change.
Six states and five territories are recognised in the ASGC: New South Wales, Victoria, Queensland, South Australia, Western Australia, Tasmania, Northern Territory, Australian Capital Territory, Jervis Bay Territory and the external Territories of Christmas Island and Cocos (Keeling) Islands.
These spatial units are political entities with fixed boundaries. Except for the last three mentioned territories, the total area of each S/T, including their off-shore islands, is used for statistical purposes as a separate spatial unit in the ASGC. Jervis Bay Territory, and the Territories of Christmas Island and Cocos (Keeling) Islands are included as one spatial unit at the S/T level under the category of Other Territories.
S/Ts consist of one or more SDs. In aggregate, they cover Australia (as defined in Chapter 1, p. 5) without gaps or overlaps.
This coding order has been widely used in the ABS and other organizations as a standard for many years. The order was reviewed when Western Australia displaced South Australia as the fourth most populous state. Citing the Commonwealth Table of Precedence, which adopted a revised listing such that any textual material having protocol significance should list Western Australia before South Australia, some users requested the code for Western Australia be changed to four and South Australia to five. For the ASGC however, the above order was maintained to ensure historical continuity, to reduce potential errors in data handling and interpreting, and to avoid costs associated with changing existing systems.
S/Ts are identified by unique one-digit codes within Australia as follows: