Statistical Area Level 2
Statistical Areas Level 2 (SA2s) are medium-sized general purpose areas built up from whole Statistical Areas Level 1 (SA1s). Their purpose is to represent a community that interacts together socially and economically.
There are 2,473 SA2s covering the whole of Australia without gaps or overlaps. This includes 19 non-spatial special purpose codes including a new Outside Australia code. These non-spatial SA2s represent populations that are difficult to define geographically such as people who are in transit or have no fixed address. These are represented by Migratory – Offshore – Shipping and No Usual Address SA2s.
SA2s are generally the smallest areas used for the release of ABS non-Census of Population and Housing statistics, including Estimated Resident Population and Health and Vitals data. Whole SA2s aggregate to form Statistical Areas Level 3 (SA3s). SA2s are also used to build Significant Urban Areas and to approximate Tourism Regions.
SA2 design criteria
SA2s are designed using multiple criteria, listed below in approximate order of importance.
SA2s generally have a population between 3,000 and 25,000 with an average of about 10,000 people. SA2s in remote and regional areas generally have smaller populations than those in urban areas. There are some SA2s outside these target population ranges due to other considerations including:
- The relative sparseness of the population in remote regions (an SA2 with a population of 3,000 may cover too large and diverse a geographic area to be meaningful).
- The benefit of preserving recognisable areas for which there is a considerable amount of historical data.
- Isolated geographic areas, such as islands or other isolated populations.
- The need to avoid subdivisions of otherwise coherent regions, such as very large suburbs or regional towns.
A functional area is the area from which people come to access services at a centre. This centre may be a rural town, a regional city, a commercial and transport hub within a major city, or the major city itself. The concept of a functional area is used at all levels of the ABS Main Structure and is particularly essential to the design of SA2s outside of major urban areas.
A centre and its functional area are represented by one or more SA2s. A rural town and its functional area may be combined into a single SA2. A larger town may be identified by a single SA2 and its functional area around the town by a second SA2. Larger towns and regional cities may be represented by several SA2s.
Within cities, SA2s represent gazetted suburbs rather than functional areas.
In remote areas, SA2s are designed to represent meaningful regions, useful for statistical analysis.
SA2s containing regional towns or on the fringes of larger cities are designed to contain the urban area, any immediately associated semi urban development, and likely growth areas in the next 10 to 20 years. This is to ensure that the SA2 boundaries remain stable over several population and housing censuses.
Suburbs and Localities (or rural suburbs)
Where possible, SA2s consist of whole gazetted suburbs or rural localities. This is to make the regions as meaningful as possible to users unfamiliar with statistical geography and to facilitate address coding to other ASGS units.
In regional and remote areas, gazetted localities are usually too small to be represented by a single SA2 and are combined with neighbouring areas to represent a functional area or other meaningful region.
In major cities, SA2s often represent single suburbs. Suburb size is variable within and between cities and they do not always make a convenient region to be used directly as an SA2. Where this occurs, five general criteria are used to cluster smaller suburbs together or break up extremely large suburbs:
- shared road networks
- shared community facilities
- Local Government Areas
- shared historical or social links
- socio-economic similarity
Local Government Areas
Local Government Areas (LGAs) are considered in the design of SA2s and are often adopted where the LGA boundary satisfies one or more of the following:
- it closely aligns with gazetted suburb boundaries
- it reflects the underlying settlement pattern
- it represents the functional area of a regional town or city
- it has a high degree of recognition among stakeholders
- it aligns to a significant recognisable geographic feature
Zero SA2s have a nil population. They are created to represent large unpopulated areas that are not easily combined with surrounding populated SA2s.
They may include:
- major infrastructure (such as ports and airports)
- significant bodies of water
- major commercial and industrial zones
- national parks
- defence land
- very large urban parks
- very large sporting precincts
SA2 name criteria
The key criteria for SA2 names are that they be:
- have a maximum of 50 characters
- unique, that is not shared by any other SA2 in Australia
In large urban areas, SA2s are named for the gazetted suburbs they contain.
- Where an SA2 is made from a single suburb, it will retain the name of the suburb, for example “Curtin”.
- Where a single large suburb is split into more than one SA2, it will retain the name of the suburb and a geographic identifier, for example “Mount Waverley – North”.
- Where an SA2 is made up from 2 or 3 suburbs, the SA2 name is a concatenation of the suburb names, for example “Greenfield Park – Prairiewood”.
- Where an SA2 is made up of 4 or more suburbs it will be named for the larger or more prominent suburbs, or given a local identifier, for example “Belgrave - Selby”.
In rural areas, SA2s are named for the gazetted localities they contain, or the towns, cities, or regions with which they are associated, for example:
- Benalla Surrounds
- Townsville – South
- Bulahdelah – Stroud
In previous editions of the ASGS, SA2s surrounding towns have been referred to as “X Region”, even when the town was not included in that SA2. In ASGS Edition 3, SA2s which do not include the town have been renamed to “X Surrounds” to reduce confusion. For example, “Cooma Region”, does not include the town of Cooma so it has been renamed to “Cooma Surrounds”.
Where an SA2 name appears in two or more State and Territories, the State or Territory abbreviation is attached to the SA2 name, for example:
- O’Connor (ACT)
- O’Connor (WA)
SA2 coding structure
An SA2 is identifiable by a 9-digit fully hierarchical code comprising the 1-digit State or Territory identifier, and Statistical Areas Level 2-4 identifiers. The SA2 identifier is a 4-digit code, assigned in alphabetical order within an SA3. An SA2 code is only unique within a State or Territory if it is preceded by the State or Territory identifier.
The ABS previously provided a short, 5-digit code for SA2s. Short codes are not included in ASGS Edition 3 to reduce confusion. Support is available via statistical consultancies for users that need support to transition from using 5-digit to 9-digit codes.
In the future, it may be necessary to allocate new codes. If an SA2 is discontinued, or changes significantly for new editions of the ASGS, the SA2 identifier will be retired and the replacement SA2s will be given the next available previously unused SA2 identifier within the State or Territory.