Statistical Area Level 1

Statistical Areas Level 1 (SA1s) are geographic areas built from whole Mesh Blocks. Whole SA1s aggregate to form Statistical Areas Level 2 (SA2s). SA1s are designed to maximise the geographic detail available for Census of Population and Housing data. However, limited Census of Population and Housing data may also be available at the Mesh Block level for ASGS Edition 3.

There are 61,845 SA1 regions covering the whole of Australia without gaps or overlaps. This includes 34 non-spatial special purpose codes including a new Outside Australia code. These non-spatial SA1s represent populations that are difficult to define geographically such as people who are in transit or have no fixed address. Examples include the Migratory and No Usual Address SA1s.

SA1s are also used as the building blocks for some ASGS geographies, including the Indigenous Structure, Significant Urban Areas, Urban Centres and Localities, Section of State Structure, and the Remoteness Structure.

SA1s are designed using multiple criteria, listed below in approximate order of importance.

SA1s generally have a population of 200 to 800 people, and an average population of about 400 people. SA1s in remote and regional areas generally have smaller populations than those in urban areas. Some low population count SA1s were permitted to accommodate other design criteria.

SA1s are designed to represent Aboriginal and Torres Strait Islander communities as accurately as possible, particularly in remote areas.

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 of over 200 people per square kilometre
• built infrastructure including: ports, airports with paved runways, industrial, commercial and retail development, large sporting complexes, education campuses, places of worship, military camps and research stations
• local parks and playgrounds
• local sports facilities and ovals
• vegetation corridors
• golf courses
• cemeteries
• lakes, rivers, riverbanks, creeks and drainage reserves surrounded by development of an urban character
• sewerage facilities, waste disposal facilities, hospitals, transport hubs, and grain storage

Rural SA1s contain one or more of the following:

• residential development with a density of less than 200 people per square kilometre
• agriculture
• national parks
• defence reserves
• indigenous lands
• mines
• stockyards
• lakes, rivers, riverbanks, creeks and drainage reserves not surrounded by development of an urban character

SA1s are generally internally connected by road transport. Exceptions include islands, which are either combined with the nearest onshore SA1 or grouped with other islands.

Where possible, SA1s are 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 are sometimes too small to represent as an SA1. Smaller localities are grouped together based on their Local Government Area, the use of shared road networks, the use of shared community facilities, and landscape features such as location within a valley.

SA1s are created in anticipation of development which is likely to occur before the date of the 2021 Census of Population and Housing.

Prisons, remand centres and juvenile detention centres with a population of over 200 people are generally represented by their own SA1.

Defence bases with a population of over 200 people are generally represented by their own SA1.

Zero SA1s are SA1s with a nil 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:

• airports
• ports
• 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 to ever be populated, for example extreme desert or otherwise inhospitable terrain
• lakes

SA1s are not named.

SA1s are identified by an 11-digit fully hierarchical code, comprising the 1-digit State and Territory, and Statistical Areas Level 1-4 identifiers. The SA1 identifier is a 2-digit code, assigned within an SA2. An SA1 code is only unique within a State or Territory when it is preceded by the State or Territory identifier.

The ABS previously provided an additional, short 7-digit code for SA1s. 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 7-digit to 11-digit codes.

In the future, it may be necessary to allocate new codes. If an SA1 is discontinued, or changes significantly for new editions of the ASGS, the SA1 identifier will be retired and the replacement SA1s will be given the next available previously unused SA1 identifier within the SA2.