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. 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 diagram 3, Chapter 1).
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:
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.
More specifically, the SDs within the individual S/T have been delimited as follows:
- 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.
- 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.
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.
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)
The coding conventions for SDs are as follows:
- 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.
- 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). Example: 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 9).
- 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.