Postcodes & Postal Areas
|What are postcodes?A postcode is a four digit number used by Australia Post to assist with mail delivery. Australia Post does not currently define geographic boundaries for postcodes. However, a number of organisations, such as PSMA Australia Limited, create geographic boundaries that aim to define the geographic extent of the mail delivery area for each postcode. Defining postcodes with a geographic boundary is an imprecise process, and this is demonstrated by the fact that there are variations in boundaries released by different organisations.|
Postcodes cover most, but not all, of Australia; for example, western Tasmania is not covered by a postcode.
Because postcodes are a well-known and easily collected component of an address, they are used by many researchers and businesses as a way of linking data to a geographic area for spatial analysis. The ABS provides ‘Postcode Indexes’ that can be used to link data collected with a postcode to standard ABS geographic areas – for example, Statistical Divisions (SDs) and Remoteness Areas (RAs) within the Australian Standard Geographical Classification (ASGC) or Statistical Areas Level 4 (SA4s) and Greater Capital City Statistical Areas (GCCSAs) within the Australian Statistical Geography Standard (ASGS). This enables data to be directly compared with a range of other ABS data that is released on both the ASGC and the ASGS. For a full list of coding indexes available, please view the ‘Correspondences’ chapter of the ABS Statistical Geography website: http://www.abs.gov.au/geography.
What are ABS Postal Areas and what is their purpose?Postal Areas (POAs) are an ABS approximation of postcodes created to enable the release of ABS data on areas that, as closely as possible, approximate postcodes. This enables the comparison of ABS data with other data collected using postcodes. POAs are approximated using one or more Statistical Areas Level 1 (SA1s) from the ASGS. SA1s are the smallest geographic areas on which Census data are released. Previously, POAs were defined using aggregations of Census Collection Districts (CCDs).
POAs are defined to cover the whole of geographic Australia. However, Unclassified POAs, which represent areas not covered by postcodes, are not represented as spatial objects in the POA digital boundaries.
POAs are incorporated into the ASGS as a non-ABS structure. These are geographic areas that approximate administrative or environmental boundaries which are not defined by the ABS, but are important to users of ABS statistics. Diagram 1 illustrates how POAs (in orange) relate to other ABS and non-ABS structures.
Diagram 1 ASGS non-ABS structures and 2011 SLA
How were POAs created?In developing POAs, each SA1 is allocated an Australia Post postcode. POAs derived in this way only approximate Australia Post postcode boundaries. SA1 allocations are based on the distribution of dwellings, not on area. This means that an SA1 is allocated to the postcode to which it contributes the most dwellings. POAs are then formed by joining the SA1s that have been allocated the same postcode.
Allocations have been determined using the best available information on postcode boundaries. Unfortunately, official postcode boundaries have not been updated since the early 1990s and none of the more recent interpretations have been endorsed by Australia Post. Users should be aware of these limitations when using the POA classification.
Unallocated postcodesSome Australia Post postcodes are not included in the POA classification. This occurs when no SA1 can be allocated to a particular postcode. There are two situations when this occurs where:
A list of delivery area postcodes not included in the POA classification is provided at the end of this document.
The POAs also exclude Australia Post postcodes that are not street delivery areas. These include post office boxes, mail back competitions, large volume receivers and specialist delivery postcodes. These postcodes are only valid for postal addresses and are not a valid location for population data.
POAs that cross state or territory bordersWhere POAs cross state or territory borders, standard Census products will provide data for the entire POA. The following table lists these POAs.
Working with data on POAsWhen working with data on POAs, it is important to remember that the POAs are approximations, using SA1s, of the postcode boundaries and that the data relate to the POA boundary and not to the postcode boundary. The POA classification also excludes some postcodes and therefore, there will be no Census data for these postcodes.
In some cases, users of Census data may have trouble reconciling their own postcode based statistics with Census data because:
What data will be available on POAs?Data from the 2011 Census of Population and Housing will be available for POAs.
Where can I get the POA boundaries?POA boundaries are available in MapInfo Interchange and ESRI Shapefile formats and can be downloaded from the ‘ABS Geography Publications’ chapter of the ABS Statistical Geography website: http://www.abs.gov.au/geography.
DataPacks contain 2011 Census Community Profile data for all of Australia and corresponding digital boundary map files. To find out more about DataPacks, visit the DataPacks page.
Where can I get further information?A detailed discussion of the POAs and the criteria used in their design can be found at: Australian Statistical Geography Standard (ASGS): Volume 3 – Non ABS Structures, July 2011 (cat. no. 1270.0.55.003).
More information on the ASGS and ABS Statistical Geography can be found at: Australian Statistical Geography Standard: Volume 1 Main Structure and Greater Capital City Statistical Areas, July 2011 (cat. no. 1270.0.55.001) or by visiting the ABS Statistical Geography website: http://www.abs.gov.au/geography.
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Unallocated delivery area postcodesThe following tables list the delivery area postcodes for each state and territory that were not included in the POA classification.