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PURPOSE

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 Chapter 15, Maps.

THE STRUCTURE

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 (as defined in Chapter 1) without gaps or overlaps.

Tables

Detailed tables of the Main Structure are shown in Chapter 14, The Classification Structures.

For example:

• Main Structure - Broad

• Main Structure - Detailed

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).

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 2006 edition, many urban CDs are of a size such that census collectors may be 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 2006 Census, 38,704 CDs were defined throughout Australia. A listing of CDs within SLAs by S/T is available from the ABS web site, Australian Standard Geographical Classification (ASGC) Concordances, 2006 (cat. no. 1216.0.15.002).

Delimitation of CDs

For 2006 Census the following standard CD design principles were used for delimiting CDs:

• 2001 Census CD boundaries should be retained wherever possible.
• CDs should be designed as the smallest spatial units of collection for the Population Census and be capable of aggregation to form larger spatial units.
• CD boundaries must conform with SLA boundaries, which in turn conform with LGA boundaries. Since all other boundaries for the census edition of the ASGC are created by aggregation of CDs, CDs automatically conform to these other ASGC boundaries.
• CD boundaries, wherever practical, should also conform to the following non-ABS boundaries - gazetted Suburb/Locality boundaries, Commonwealth Electoral Divisions (CED) and State Electoral Divisions (SED). In 2006, where new CDs are defined in growth areas, CD design should take into account these non-ABS boundaries. However, if no other changes are needed, boundaries should not be changed merely to improve their alignment to non-ABS boundaries.
• The area, population and dwellings delimited by a CD boundary must not be so great that one collector cannot deliver census forms within about ten days. In urban areas one or more CDs can be combined to create a single collector's workload (CLW).
• The chosen CD boundaries should, if possible, be readily identifiable on the ground. They should be defined in terms of permanent features and follow the centre of the road or river if these features are used. However, the use of major roads as CD boundaries in rural areas should be avoided where possible to minimise the splitting of identifiable rural localities. In addition, the chosen CD boundary should delimit CDs which conform to existing and proposed land uses (i.e. rural property boundaries and proposed suburban development).
• CDs should not be designed in such a way as to prevent publication of data for confidentiality reasons. Accordingly, a CD, which is not a deliberate Nil CD, should contain, where possible, at least 100 persons at the next census. For dissemination purposes, Indigenous Community CDs should contain at least 80 persons.
• CDs in aggregate must cover the whole of Australia (as defined in Chapter 1) without gaps or overlaps.

• Commercial or Industrial Area CDs - are defined for buildings predominantly used for commercial trade or work intended for both retail and wholesale trade. They may also include factories, plants, and warehouses used for industrial/manufacturing purposes.
• Construction and/or Mining CDs - are defined when the construction camp is located adjacent to or within close proximity of a major building or mine development project and is expected to exist for at least two censuses.
• Defence Establishments CDs - are created for cluster of residential dwellings (and related amenities) specifically occupied by or built for defence force personnel. Unlike 2001, all Defence CDs will have a defined geographic location in 2006, that is, there are no Defence point CDs.
• Deliberate Nil CDs - are created for areas where it is not expected that persons or dwellings will be enumerated on census night. 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.
• Ethnic Area CDs - are defined for areas with high concentrations of one or more ethnic groups with a predominance of householders that eg. non-English speaking.
• Holiday Areas CDs - are created to identify areas with a seasonal transient holidaying population, and at the time of the census could contain either a high or low occupancy rate.
• Indigenous Community CDs - are defined where there is a significant Indigenous population.
• Migrant Detention Centres (Permanent) CDs - are defined for permanent migrant detention centres.
• 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. Any person enumerated on a Water CD is subsequently transferred to the default land-based CD at the time that the census forms are processed. Therefore, water CDs do not have any statistical data associated with them. These CDs may not be included in higher level boundary aggregations to give a more realistic representation of the Australian coastline.
• Non-Private Dwelling (NPD) CDs - include hotels, motels, hospital, nursing homes, hostels, shelter for the homeless etc.
• Non-Private Dwelling and Secure Apartment Building (NaSAB) CDs - are defined for high proportion of secured apartments buildings and Non-Private Dwellings (eg. hotel, motels, hospitals, etc).
• Private Dwelling Establishments (PDE) CDs - are defined for areas with a high proportion of Private Dwelling Establishments (known as Other Dwellings CDs in 2001) and include caravan parks, manufactured home states, marinas, retirement villages and mixed occupancy apartment complexes.
• Point CDs - are created when a specific community or establishment has a central location but where some or all of the members of the community or establishment are not fixed at that specific location on census night, although they are counted as being at that location. They have no defined boundaries and are represented as points. These CDs include Migratory, Shipping CDs, Offshore CDs and may include Indigenous communities, or mining or construction camps.
• Secured Apartment Buildings (SAB) CDs - this new category of SAB CD has been created to address the enumeration problems often faced by collectors when gaining access to secured apartments. These are predominantly located in the CBDs of major urban centres.
• Snowfields CDs - contains predominantly accommodation establishments or dwellings which house transient seasonal populations. These CDs are within close proximity of recreational areas that provide activities relating to the snowfields.
• Prison CDs - contains buildings (including remand areas) which house adult inmates and are administered by the State Departments of Corrective Services, or on their behalf by private organisations. These buildings will directly relate to the housing and support of inmates and are usually found within the boundary of a prison complex or campus.
• Off-shore CDs (including Oil Rigs and Antarctic Enumeration) - are designed to facilitate the recording of people on census night who are off-shore on all structures (such as oil and gas drilling rigs) in Australian waters or those structures outside Australian waters for which immigration formalities are not required to be completed. They are not spatial units in the usual sense as they do not have defined boundaries.
• Shipping CDs - covers an area of water, normally a port, which is controlled by a Port Authority. Shipping CDs have defined boundaries. They are designed to record people who are on board vessels in or between Australian ports on Census night.
• Migratory CDs - are used to record all people who are in transit on long distance trains, buses, aircraft and long haul road transport vehicles on census night. The crew and staff of both passenger and other commercial land and air transport are also attributed to the Migratory CD. They are not spatial units in the usual sense as they do not have defined boundaries.

CD codes

CDs are identified by unique six-digit codes within each S/T.

Example:

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). 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 1,426 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 Chapter 14, 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, 484 of the total 1,426 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-Simpson 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 some 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 to encompass off-shore, shipping and migratory CDs.

SLA name

The naming conventions for SLAs are as follows:

• 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.
• An SLA which is part of an LGA may adopt a hyphenated name the first part of which is the name of the LGA.

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.

Latrobe (M) - Pt A
Latrobe (M) - Pt B


• An SLA which is part of an LGA may adopt a locality or suburb name.

Acacia Ridge
Albion
Yeronga
Zillmere


• 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))

• 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, Local Government Area Structure, Chapter 2, Main Structure or Chapter 10, Special Purpose Codes respectively).

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 (see Chapter 10, Special Purpose 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.

• SSDs consist of one or more SLAs. In aggregate, they cover Australia (as defined in Chapter 1) 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). 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:

• 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.

• One or more SSDs must be defined for an S Dist. that falls within an S/T.

• One or more SSDs must be defined for each part of an S Dist. which straddles an S/T boundary.

• 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.

• One Off-Shore Areas & Migratory SSD is defined for each S/T except the Australian Capital Territory.

• 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).

• SSD code 88 has been reserved for special purposes (see Chapter 10, Special Purpose 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) without gaps or overlaps. SDs aggregate to form S/Ts (see ASGC Structural Chart, Chapter 1).

In this edition of the ASGC, there are 69 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:

• 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.

• 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. The 2006 edition of the ASGC introduces major changes to the SDs in south east Queensland to reflect the patterns of development in this area. The Gold Coast, Sunshine Coast and West Moreton are now represented by their own SDs. The Brisbane SD has been adjusted and the Moreton SD has been abolished.
• 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.

Example:

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).

Adelaide 405
Kimberley 545


• The SD code 85 is reserved for Off-Shore Areas & Migratory SDs and the SD code 88 has been reserved for special purposes (see Chapter 10, Special Purpose 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) without gaps or overlaps.

S/Ts are identified by unique one-digit codes within Australia as follows: