Mesh Blocks are the smallest geographic areas defined by the ABS and form the building blocks for the larger regions of the Australian Statistical Geography Standard (ASGS). They broadly identify land use such as residential, commercial, primary production and parks. Statistical Areas Level 1 (SA1s) are generally the smallest geographic unit used to release Census of Population and Housing data; however, for ASGS Edition 3, limited Census of Population and Housing data may also be available at the Mesh Block level.

ASGS Edition 3 contains 368,286 Mesh Blocks covering the whole of Australia without gaps or overlaps. This includes 114 non-spatial special purpose codes including a new Outside Australia code. These non-spatial Mesh Blocks represent populations that are difficult to define geographically such as people who are in transit or have no fixed address. Migratory and No Usual Address are examples of this type of Mesh Block.

The Non ABS structures that will be approximated from Mesh Blocks include Local Government Areas, Postal Areas, Suburbs and Localities (formerly State Suburbs), Commonwealth Electoral Divisions, State Electoral Divisions, Australian Drainage Divisions and Destination Zones.

As Mesh Blocks are very small they can be combined together to accurately approximate a large range of other geographies.

Mesh Blocks for ASGS Edition 3 are designed according to a standard set of criteria first developed for ASGS 2011. All of the criteria considered are listed below in approximate order of importance.

Please note that the order of importance for some criteria may change depending on whether an area is urban or rural. For example, in urban areas, the requirement for dwelling counts over 30 takes precedence over the requirement to match locality boundaries. In rural areas however, matching locality boundaries sometimes takes precedence over minimum dwelling requirements because of the flow on effect Mesh Block design has on other structures in the hierarchy. 

Mesh Blocks reflect dominant land use where possible. For example, residential areas are separated from commercial or industrial areas. Wherever possible, each Mesh Block is designed to have a single land use, for example parkland, but this is not always possible. Land use is recorded in the Mesh Block category attribute according to the criteria below. 

• Residential: will mainly contain houses, duplexes, apartments, townhouses, gated communities, caravan parks, retirement villages, residential military bases, and prisons. Where possible, residential areas are separated from other land uses.
• Commercial: will contain a number of businesses, and where possible, will have a zero population count. Some commercial Mesh Blocks may contain population, for example, where a residential flat is above a shop.
• Industrial: will contain a number of businesses, and where possible, will have a zero population count.
• Parkland: will mainly contain parks, nature reserves, public open space, and other minimal use protected or conserved areas and, where possible, will have a zero population count. Parkland Mesh Blocks may also include sporting arenas or facilities, including racecourses, golf courses and stadiums. These facilities may not be open to the public.
• Education: will contain education facilities, and may contain population in non-private dwellings such as boarding schools or universities.
• Hospital/Medical: will contain hospital or medical facilities. This may include aged care facilities, which are distinguished from larger retirement villages.
• Transport: will contain road or rail features and, where possible, will have a zero population count.
• Primary Production: a Mesh Block is classified as Primary Production when available information indicates that more than half of the area is used for primary production.
• Water: will mainly contain various bodies of water including lakes, rivers and canals, and where possible will have a zero population count.
• Other: includes Mesh Blocks which could not be easily placed in one of the other nine categories due to the nature of the land use, or due to evidence of high mixed use. Many Mesh Blocks which were classified as agricultural in earlier editions of the ASGS are now classified as other.

Mesh Blocks are designed where possible to contain between 30 and 60 dwellings, with some low dwelling count Mesh Blocks permitted to accommodate other design criteria. The minimum dwelling count of Mesh Blocks is designed to be small enough to aggregate accurately to a wide range of areas and to enable a ready comparison of statistics between geographic regions. The Mesh Block target size helps the ABS protect against accidental disclosure of confidential information.

Zero Mesh Blocks are created to capture areas with no population, such as airports, commercial or industrial developments, and large shopping complexes.

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

Where practical, Mesh Block boundaries do not cross cadastral (property) boundaries. Mesh Blocks are designed to be an aggregation of land parcels.

Mesh Blocks follow road centre lines where possible. Roads, particularly major roads such as highways and motorways, are used as Mesh Block boundaries where possible.

Each Mesh Block is a single area, for example every island is a single Mesh Block.

Where possible, Mesh Blocks are designed to contain or aggregate to whole officially gazetted suburbs or localities, especially in rural areas.

Mesh Blocks, where possible, contain an entire major facility. This includes hospitals, universities, airports, correctional centres, and retirement villages, which occupy a large area of land, extend across both sides of a street, or have an internal road network.

High density housing (such as apartment blocks) have been identified and are included in individual Mesh Blocks of compact shape, where possible. This means that some Mesh Blocks have more than 60 dwellings.

Mesh Blocks aim to group communities of interest together. For example, a whole apartment building, residential complex, parking lot, shopping complex or retirement village is contained in one Mesh Block, if possible.

Where possible in urban areas, Mesh Blocks reflect town blocks.

Where possible, all dwellings/buildings are to be accessible by road or pathway from within the Mesh Block so that communities of interest are grouped together. For example the houses on a cul-de-sac are contained in one Mesh Block and therefore boundaries may follow a back fence.

Where practical, Mesh Blocks are designed to be compact in size and shape, especially in urban areas.

Natural and man-made barriers, such as main roads, are used as boundaries in order to keep communities together. This means that if a Mesh Block boundary runs along a main road then adjacent Mesh Block boundaries will follow the same road if possible. This will provide consistency and continuity in the aggregated regions made from Mesh Blocks.

Mesh Block boundaries reflect topographic, or landscape, features where practical.
The topographic features used for Mesh Block design include:

• water bodies such as rivers and lakes
• transportation such as roads and rail
• open space such as parkland, nature reserves and forest
• major mountain ranges or escarpments

Mesh Blocks are not named. 

The 11-digit Mesh Block code comprises: State and Territory identifier (1 digit), and a Mesh Block identifier (10 digits).

Some Mesh Block redesign has occurred for the release of ASGS Edition 3. This redesign is necessary to ensure that Mesh Blocks continue to meet the criteria set out above, and so that they remain relevant by reflecting the growth and change in Australia's population, economy and infrastructure.

Changes to Mesh Block boundaries occur where growth and development have taken place since the last edition of the ASGS in 2016. Boundaries were modified in the simplest way possible to facilitate comparison over time. Where changes were made, they were undertaken to ensure long term stability into the future.

This redesign has in turn affected the coding of the Mesh Blocks. Where a 2016 Mesh Block has been split or significantly redesigned, the original 2016 Mesh Block code has been retired and replaced with a new, previously unused code for ASGS Edition 3.

Some design changes to boundaries that reflect changes to physical infrastructure, such as realigned roads, do not result in the movement between Mesh Blocks of substantial numbers of households or businesses, or land area. These changes have been made for cartographic purposes to ensure that the ASGS boundaries can be used with standard mapping data. They are not considered to be significant and have not resulted in code changes.

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.

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.

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.

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 (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

The key criteria for SA2 names are that they be: 

• meaningful
• 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)

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.

Statistical Areas Level 3 (SA3s) are geographic areas built from whole Statistical Areas Level 2 (SA2s). They are designed for the output of regional data, including 2021 Census of Population and Housing data. SA3s create a standard framework for the analysis of ABS data at the regional level through clustering groups of SA2s that have similar regional characteristics. Whole SA3s aggregate to form Statistical Areas Level 4 (SA4s).

There are 359 SA3s 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 SA3s 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 SA3s.

The Other Territories of Jervis Bay, Cocos (Keeling) Islands, Christmas Island and Norfolk Island are each represented by individual SA3s.

SA3s are designed using multiple criteria, listed below in approximate order of importance.

In general, SA3s are designed to have populations between 30,000 and 130,000 people. However, the creation of meaningful regional areas takes priority over population criteria. As a result, there are some SA3s with populations above 130,000 or below 30,000.

SA3s are often the functional areas of regional towns and cities with a population in excess of 20,000 or clusters of related suburbs around urban commercial and transport hubs within the major urban areas.

SA3s create a standard framework for the analysis of ABS data at the regional level through clustering groups of SA2s that have similar geographic and socio-economic characteristics. In many cases, these areas are defined by existing administrative boundaries, such as State Regional Development Areas or one or more Local Government Areas.

Zero SA3s have a nil population. They are created to represent large unpopulated areas that are not easily combined with surrounding populated SA3s, such as large national parks on the fringes of large urban areas.

The key criteria for SA3 names are that they be: 

• meaningful
• have a maximum of 50 characters
• unique, that is not shared by any other SA3 in Australia

SA3s are named according to the areas they represent.

• Where an SA3 represents a well-known regional area or a State Regional Development Area it is named after that region, for example “Southern Highlands”.
• Where an SA3 represents the functional area of a regional city it is named after that city, for example “Wagga Wagga”. In some cases the name of an associated town or region is also included, for example “Griffith - Murrumbidgee (West)”.
• Where an SA3 represents an economic hub within a major city it is generally named to reflect that hub, for example “Parramatta”.
• Where an SA3 represents a group of related suburbs it is named after one or more of those suburbs that reflect its location, for example “North Sydney – Mosman”.
• Where an SA3 name is not unique within Australia, it is followed by the State and Territory abbreviation in brackets, for example “Central Highlands (Tas.)”.

SA3s are identified by 5-digit hierarchical codes. This comprises a 1-digit State or Territory identifier followed by a 2-digit SA4 identifier, unique within each State and Territory, and a 2-digit SA3 identifier, unique within each SA4.

Statistical Area Level 4 (SA4s) are geographic areas built from whole Statistical Areas Level 3 (SA3s). SA4s are the largest sub-state regions in the Main Structure of the ASGS and are designed for the output of a variety of regional data, including data from the 2021 Census of Population and Housing. SA4 boundaries represent labour markets and the functional area of Australian capital cities respectively. They are designed with an emphasis on stability over time to support the time series of statistical releases such as the Quarterly Labour Force publication. These areas represent labour markets or groups of labour markets within each state and territory.

Whole SA4s aggregate to Greater Capital City Statistical Areas and States and Territories. There are 108 SA4s 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 SA4s 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 SA4s.

The Other Territories of Jervis Bay, Cocos (Keeling) Islands, Christmas Island and Norfolk Island are together represented by a single SA4.

SA4s are designed using multiple criteria, listed below in approximate order of importance.

Most SA4s have a population above 100,000 people to provide sufficient sample size for Labour Force estimates. In regional areas, SA4s tend to have smaller populations of 100,000 to 300,000 people. In cities, SA4s tend to have larger populations of 300,000 to 500,000 people.

SA4s are designed to incorporate both labour supply (where people live) and demand (where people work). This enhances the quality of statistical outputs related to labour markets.

The ABS consulted with experts on labour market geography and undertook analysis of the Census of Population and Housing travel to work data to identify labour markets within Australia. The resulting labour markets are characterised by a large number of very small regional labour markets, a smaller number of medium sized labour markets around regional centres, and very large labour markets representing the major city centres. While this may be an accurate reflection of Australian labour markets, many of the regions did not meet the minimum population criterion.

SA4s are designed to represent the labour markets of the largest regional cities such as Wollongong, Bendigo and Townsville. SA4s present specific labour force data on these cities’ labour markets.

In outer regional and remote areas, labour markets tend to be small and localised around regional towns. SA4s in these areas represent aggregations of these labour markets based on geographic, social and economic similarities. SA4s which contain only remote and regional areas enable a picture of regional and remote labour force activity to be presented.

Smaller regional labour markets are combined based on travel to work interactions, as well as industry and regional similarities, to create SA4s of about 100,000 to 300,000 people. Medium sized regional centre labour markets that exceeded 100,000 people (for example Cairns, Qld) are preserved as far as possible as SA4s that directly represent the labour market, though in some cases small closely related labour markets are included in these SA4s. Very large labour markets of 300,000 to 500,000 people are split to reflect major employment hubs and their main labour supply catchments.

The key criteria for SA4 names are that they be: 

• meaningful
• have a maximum of 50 characters
• unique, that is not shared by any other SA4 in Australia

SA4s are named according to the areas they represent:

• Where an SA4 represents a labour market of a major city it is named after that city, for example “Bendigo”.
• Where an SA4 represents an employment centre within a larger city it is generally named to reflect both the larger city and the employment centre or part of the city that it represents, for example “Melbourne - Inner South”.
• Where an SA4 represents a collection of labour markets in regional areas it is named using either a description of that part of the state and territory or after one or more well-known regional areas that it closely replicates, for example “Latrobe – Gippsland”.
• Where the name does not identify it within Australia, it is generally preceded by the State or Territory name, for example “Western Australia - Wheat Belt”.

SA4s are identified by a 3-digit hierarchical code. This comprises a 1-digit State or Territory identifier, which precedes a 2-digit SA4 identifier, unique within each State and Territory.

Greater Capital City Statistical Areas (GCCSAs) are geographic areas built from Statistical Areas Level 4 (SA4s). GCCSA boundaries represent labour markets and the functional area of Australian capital cities respectively. They are designed with an emphasis on stability over time to support the time series of statistical releases such as the Quarterly Labour Force publication.

There are 16 GCCSAs covering the whole of Australia without gaps or overlaps. The GCCSA boundaries may differ from official or commonly applied area boundaries. There are 8 regions covering each of the Australian state and territory capital cities; 7 regions covering the rest of each state and the Northern Territory (ACT only has one GCCSA region for the entire Territory); and a region covering Other Territories which includes Jervis Bay, Christmas Island, Cocos (Keeling) Islands and Norfolk Island.

In addition to these 16 GCCSA regions are 19 non-spatial special purpose codes, for a total of 35 GCCSAs. These non-spatial GCCSAs represent populations that are difficult to define geographically such as people who are in transit or have no fixed address. These special purpose codes include Migratory – Offshore – Shipping and No Usual Address for each State and Territory, as well as a new Outside Australia code.

GCCSAs are designed to represent the functional area of each of the eight State and Territory capital cities which includes populations who regularly socialise, shop or work within the city, but may live either in the city or in the small towns and rural areas surrounding the city. Within each State and Territory, the area not included in the GCCSA is represented by a Rest of State region. GCCSAs do not have population criteria.

GCCSAs are named according to the cities they represent, for example “Greater Sydney”. The remainder of the State and Territory is named Rest of <State>, for example “Rest of NSW”. The exceptions to this are the ACT, as the whole of the ACT is included in the GCCSA, and the Other Territories, which do not have a capital city.

A GCCSA is identified by a 5-character alphanumeric code. This comprises a 1-digit State or Territory identifier followed by a 4-character GCCSA identifier that is unique within each State and Territory.

Australia is the largest geographic area in the Main Structure of the ASGS. The ASGS uses the geographic definition of Australia described in further detail in the definition of Australia section of this publication.

To align with the ISO 3166 standard, the ASGS Edition 3 code for Geographic Australia is identified by the unique three-character alpha code of AUS which replaces the three-digit numeric code of 036 (also ISO 3166 standard) as used in ASGS 2016.

Australia is broken up into the States and Territories that are separately recognised in the ASGS: 

• New South Wales
• Victoria
• Queensland
• South Australia
• Western Australia
• Tasmania
• Northern Territory
• Australian Capital Territory
• Other Territories (Jervis Bay Territory, Territory of Christmas Island, Territory of the Cocos (Keeling) Islands and Norfolk Island)

The ASGS State and Territory boundaries are a cartographic representation of legally designated boundaries and therefore should not be used for legal purposes. In general, the total area of each State and Territory, including their offshore islands, is used for statistical purposes as a separate geographic area in the ASGS. However, the Jervis Bay Territory, and the Territories of Christmas Island, Cocos (Keeling) Islands and Norfolk Island are included as one geographic area at the State and Territory level under the category of Other Territories.

States and Territories consist of one or more Statistical Areas Level 4 (SA4). In aggregate, they cover Australia without gaps or overlaps.

States and Territories are identified by unique one-digit codes as follows:

Special purpose codes allow address data to be coded to a non-spatial value. This occurs where there is insufficient information to code to a physical geographic area. For example, where someone is in transit on Census of Population and Housing night or where an incomplete address has been supplied.

• Migratory - used to code people who are in transit on long distance trains, buses, aircraft and long haul road transport vehicles on Census of Population and Housing night.
• Offshore - used to code people living offshore for example on oil rigs and drilling platforms. It is also used for expeditioners in the Australian Antarctic Territory.
• Shipping - used to code people who are on board vessels in Australian waters which are in, or between, Australian ports on Census of Population and Housing night. For Mesh Blocks there are multiple Shipping special purpose codes that represent individual ports.
• Outside Australia - used to facilitate particular ABS statistical releases. It does not have a geographic region and has a code of “ZZZZ” so that it can be easily distinguished from all other geographies.
• No Usual Address - used to code people with no fixed residential address.

The following examples show the special purpose code structure for Mesh Blocks in NSW.

ABS collections use various conventions to denote circumstances such as: not applicable, and overseas visitors.

Overall, the Main Structure and Greater Capital City Statistical Areas (GCCSAs) provides high stability and good statistical comparability to ASGS 2016. Changes to Mesh Blocks, Statistical Areas Level 1 (SA1s) and Statistical Areas Level 2 (SA2s) mainly reflect population growth, largely on the edge of urban areas. In this edition there are no major changes to Statistical Areas Level 3 (SA3s), Statistical Areas Level 4 (SA4s), or GCCSAs.

All boundaries have been aligned with updated state and territory borders. Figure 2 shows an example of this type of change. There may also be other alignment changes to align with source data. These are very minor differences in cartographic representations to the ASGS boundaries and are not considered significant.

Alignment shifts for state and territory borders will be evident in area correspondences between ASGS Edition 3 and previous ASGS editions. However, most population based correspondences will not be affected as alignment has not affected any dwellings.

When analysing population data, ASGS Edition 3 can be successfully compared to previous editions of the ASGS for time series. There may be some cases, for example when using environmental data, where alignment changes will need to be considered.

Alterations to Mesh Blocks, SA1s and SA2s are made, primarily through splitting areas, to mirror changes occurring on the ground, such as new housing developments or altered transport infrastructure. These changes reflect recent population growth, and allow users to access meaningful statistics on communities of interest. The resulting net increase in numbers of Mesh Blocks, SA1s and SA2s is shown below.

The number of both Mesh Blocks and SA1s has increased, by 2.8% and 7.5% respectively. A relatively small number have changed; 1% of Mesh Blocks and 4% of SA1s changed since ASGS Edition 2 (2016), as shown in Figure 3. This very small amount of change is mainly due to splitting large areas in growth areas into two or more smaller areas.

Changes to SA2s are similar, with an increase of 7% for ASGS Edition 3. Only 8% of 2016 SA2s changed as shown in Figure 2. These changes were made to improve data accessibility and reflect high growth, particularly in some inner city SA2s which were previously close to the 25,000 person threshold.

The only changes to the boundaries for SA3s, SA4s and GCCSAs are minor alignment changes. A net increase of 1 for SA3s, SA4s and GCCSAs is due to the creation of a new Outside Australia special purpose code.

The boundaries for a region have not changed unless they no longer met the design criteria.

The following principles apply to Main Structure and GCCSA design:

• Where possible, changes are accommodated by simple splits of existing regions.
• Where a simple split is not possible, they are based on merges and redistribution of whole regions from the next level down in the hierarchy.
• Regions are designed with a view to them remaining stable.
• Minor boundary alignment changes are made to maintain alignment to the underlying State and Territory boundaries, and source data for physical infrastructure and physical geography.

In accordance with these principles most of the change in ASGS Edition 3 is the result of simple splits. Figures 4a and 4b show an example of one large Mesh Block that was split into 176 smaller Mesh Blocks. This kind of design is typical for growth areas on the edge of large cities. Figures 5a and 5b show a similar design process where two large SA2s have been split into 6 smaller SA2s.

Merges were minimised in ASGS Edition 3. Where necessary, boundaries were merged to avoid cutting through existing infrastructure or a new growth area. Figures 6a and 6b show an example of two Mesh Blocks that have been merged together to ensure two halves of a showground can be address coded more accurately.

In some circumstances, simple splits and merges are not enough to account for growth and change on the ground. Where 2016 boundaries had to be both merged and split, areas are considered ‘redesigned’. This typically occurs in high growth areas where old features on the ground have been replaced by new development.

Figures 7a and 7b show an example of SA1 redesign on the edge of Caloundra on the Sunshine Coast. The 2016 SA1 boundary followed an old suburb boundary which has since been revised to accommodate new housing developments. The original areas were merged and then split into new SA1s. Redesigning boundaries in this way has minimal effect on the comparability of data over time as in previous editions of the ASGS, growth areas generally contained little or no population.

Alignment refers to small area changes that do not affect population. This type of change will be evident in area based correspondences between ASGS Edition 3 and other ASGS editions, but will not affect population based correspondences. Unlike other boundary changes, alignment does not trigger a code change.

In this edition the most significant alignment occurred along state and territory borders. All Mesh Blocks next to state borders were aligned to the official state land borders released by Geoscience Australia in 2020. These official state land borders are endorsed by the Surveyors General of each state and territory, the Spatial Information Council (ANZLIC) and the Intergovernmental Committee on Surveying and Mapping (ICSM). These changes will help ensure geospatial comparability to other State and Federal Government datasets. Future updates to state borders and the coastline, as agreed by the Surveyors General, ANZLIC and ICSM, will be adopted where applicable in future editions of the ASGS.

The codes and names associated with statistical areas change when an area is split, merged, or redesigned.

Changes in higher level statistical areas also result in code changes to the lower level regions contained within, except for Mesh Blocks as these are the building blocks. The smaller area may also be split, merged, redesigned, or may remain unchanged. This is due to the hierarchical coding system.

Alignment changes do not result in code or name changes at any level.

For more information on the ASGS code changes please refer to the tables below in the list of changes section. 

The ABS provides several resources to help users understand changes to boundaries and codes, and to help them manage the transformation of data across different ASGS editions and other geographies. These resources include ABS Maps, various correspondences and the list of changes section. 

In ASGS Edition 3, change flags have been included on all Main Structure and Greater Capital City Statistical boundaries as an attribute. This attribute informs users whether an area has changed since ASGS 2016 and what the nature of that change is.