STATISTICAL AREA LEVEL 1 (SA1)
Statistical Areas Level 1 (SA1) are geographical areas built from whole Mesh Blocks. Whole SA1s aggregate to form Statistical Areas Level 2 (SA2) in the Australian Statistical Geography Standard (ASGS) Main Structure. The SA1s have generally been designed as the smallest unit for the release of census data; however, limited census data may also be available at the Mesh Block level for the 2016 ASGS. SA1s have a population of between 200 and 800 people with an average population size of approximately 400 people.
There are 57,523 spatial SA1 regions covering the whole of Australia without gaps or overlaps. These include 33 non-spatial SA1 special purpose codes, comprising Migratory–Offshore–Shipping and No Usual Address codes for each State and Territory.
SA1s are also used as the building blocks for a number of ASGS defined regions including the Indigenous Structure, the Section of State and Urban Centre and Localities Structures, and the Remoteness Structure. Within the Non ABS Structure SA1s are used to approximate a number of administrative regions, such as Commonwealth Electoral Divisions and State Electoral Divisions.
Data from the 2016 Census of Population and Housing will be available at SA1 level.
DELIMITATION OF SA1
SA1s are designed to be either a predominantly rural or predominantly urban in character, with SA1s in rural and remote areas generally having a lower population than in urban areas. SA1s are designed to be internally connected by road, except for groups of unpopulated islands and Aboriginal and Torres Strait Islander communities, which may not be contiguous. Areas without permanent population (such as lakes, commercial areas, national parks etc.) are often represented by "zero SA1s" - these are SA1s with an effective design population of zero.
The SA1s were designed using a number of criteria which reflect a balance between respective considerations. Listed below are the criteria in the approximate order of importance.
SA1s generally have a population of 200 to 800 persons, and an average population of about 400 persons. SA1s in remote and regional areas generally have smaller populations than those in urban areas.
SA1s closely bound small rural towns with a population of 180 persons or more.
Aboriginal and Torres Strait Islander Population
SA1s are designed to identify Aboriginal and Torres Strait Islander communities with an aim to exclude as much of the non-indigenous population as possible.
SA1s closely bound Aboriginal and Torres Strait Islander communities with a population of 90 persons or more.
Urban and Rural
SA1s are designed to be either urban or rural in character.
Urban SA1s contain one or more of the following:
- residential development with a density over 200 persons per square kilometre
- built infrastructure including:
- airports with paved runways
- industrial, commercial and retail development
- large sports complexes
- educational campuses
- places of worship
- military camps
- research stations
- local parks and playgrounds
- local sports facilities and ovals
- vegetation corridors
- golf courses
- lakes, rivers, riverbanks, creeks and drainage reserves surrounded by development of an urban character
- sewerage facilities, waste disposal facilities, hospitals, transport hubs, grain storage.
Rural SA1s contain one or more of the following:
- residential development with a density less than 200 persons per square kilometre
- national parks
- defence reserves
- Indigenous lands
- lakes, rivers, riverbanks, creeks and drainage reserves not surrounded by development of an urban character.
Local Government Area (LGA)
In the ASGS, SA1s may be aggregated to closely reflect Local Government Area boundaries, but will not exactly match.
SA1s are generally internally connected by road transport. Exceptions include islands, which are either combined with the nearest onshore SA1 or grouped to form an SA1. Transport between these islands and to the mainland may occur in the form of ferries when the island population is large enough.
Gazetted Suburbs and Localities
Where possible, the SA1s have been designed to contain or aggregate to whole gazetted suburbs or rural localities. In urban areas, the gazetted suburbs usually consist of one or more SA1s.
In regional and remote areas, gazetted localities were sometimes too small to represent an SA1 in their own right. Where this occurred, four general criteria were used to cluster smaller localities:
- a shared road network
- similar physical geography
- shared community facilities
- being contained within the one Local Government Area.
SA1s have been created in anticipation of development likely to occur up to the time of the August 2016 Census of Population and Housing.
Prisons, remand centres and juvenile detention centres with a population of over 200 persons are generally represented by their own SA1.
Defence bases with a population of over 200 persons are generally represented by their own SA1.
Zero SA1s are SA1s with a nil or nominal population. They are created to represent large unpopulated areas that are not easily combined with surrounding populated SA1s.
They may include one or more of the following:
- commercial developments
- industrial developments
- large shopping complexes
- large sporting complexes
- large educational campuses
- research stations
- large cemeteries
- golf courses
- national parks
- large urban parks
- defence reserves
- restricted Commonwealth land
- groups of unpopulated islands
- very large areas of land which are unlikely ever to be populated, for example extreme desert or otherwise inhospitable terrain
Special Purpose SA1
There are non-spatial SA1s for Migratory, Offshore, Shipping and No Usual Address in each State and Territory.
SA1 CODING STRUCTURE
SA1s are not named. They are identified either by an 11-digit fully hierarchical code, or by a truncated 7-digit code comprising the State and Territory, SA2 and SA1 identifiers. The SA1 identifier is a 2-digit code, assigned within a SA2. A SA1 code is only unique within a State and Territory when it is preceded by the State and Territory identifier.
An 11-digit SA1 code is fully hierarchical, and comprises: State and Territory identifier, SA4 identifier, SA3 identifier, SA2 identifier and a SA1 identifier.
Example: SA1 50302104118
A 7-digit SA1 code is not fully hierarchical and comprises: State and Territory identifier, SA2 identifier and SA1 identifier.
Example: SA1 5104118
Future Allocation of SA1 Codes
In the future, it may be necessary to allocate new codes. If a SA1 is abolished, or changes significantly for new editions of the ASGS, the SA1 identifier will be retired and the replacement SA1(s) given the next available previously unused SA1 identifier within the SA2.
SA1 Identifier Ranges
Within each SA2, the SA1 identifier is in the data range 01 to 99.
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