Historical population methodology

Latest release
Reference period
2021
Released
16/07/2024
Next release Unknown

Introduction

Historical Population contains a wide range of historical demographic data on a variety of topics dating back as far as possible.

Sources

Historical Population data have been compiled from a wide range of sources, including:

  • Colonial censuses, State censuses, Colonial Statistical Returns, and Colonial Statistical Registers
  • Australian Demography Bulletins produced by the Commonwealth Bureau of Census and Statistics
  • Commonwealth censuses
  • ABS demography publications and collections

A summary of 19th century statistics collected by the colonial statistical bureaus can be found in the ABS publication Catalogue of Australian Statistical Publications, 1804 to 1901.

Early estimates of the Australian Aboriginal and Torres Strait Islander population have been compiled from ‘The Aboriginal Population of Australia’ by L.R. Smith (Australian National University Press for the Academy of Social Sciences in Australia, Canberra; 1980). More recent estimates have been compiled from the Census of Population and Housing, and other ABS demography collections.

Given that different sources often exist for the same data, minor discrepancies may exist between Historical Population and other sources. References to the sources used to compile the statistics in this publication are given at the bottom of each spreadsheet. Updated information may be available on the ABS website. 

Colonies, states, and territories

The states and territories featured in these data describe both the post-Federation states and territories, and the various colonies that existed prior to Federation. 

Tasmania, Victoria, and Queensland became independent from New South Wales in the years 1825, 1851, and 1859 respectively. Western Australia and South Australia came into existence in 1829 and 1836 respectively. The Northern Territory and Australian Capital Territory came under the control of the Federal Government in 1911 and thus were no longer included in the estimates for South Australia and New South Wales respectively. While the Northern Territory was replaced by the territories of North Australia and Central Australia between 1 February 1927 and 11 June 1931, their populations were combined and described as 'Northern Territory' for the purposes of this publication.

Following the 1992 amendments to the ‘Acts Interpretation Act’, geographic Australia is considered to include the Indian Ocean Territories of Christmas Island and the Cocos (Keeling) Islands. Population estimates have included these territories since the September quarter of 1993. To reflect this change, 'Other Territories' was created as a state- and territory-level category. ‘Other Territories’ include the Jervis Bay Territory (included in ACT estimates between 1915 and June quarter 1993), Christmas Island, and the Cocos (Keeling) Islands. From 1 July 2016, 'Other Territories' also includes Norfolk Island following the introduction of the Norfolk Island Legislation Amendment Act 2015.

Population counts and estimates

In this publication, the term population refers to the counts of people in Australia, regardless of the method of measurement. Historical Population uses four measures of population: actual location Census counts, usual residence Census counts, population estimates, and the estimated resident population (ERP).

Actual location Census counts count all people in Australia according to their location on Census night. This method was used for national, state, and territory Census population estimates between 1901 and 1971. In contrast, usual residence Census counts report people based on their place of usual residence, regardless of their location on Census night. This has been the primary method for Census population estimates since 1971. These counts are subject to the scope of the Census. Temporary overseas visitors in Australia are excluded from usual residence data.

Early population estimates were obtained through colonial musters and, from 1828, a series of colonial censuses. The dates of these colonial censuses are shown in the following table. 

Australian Censuses, 1828 to 1901
YearNSWVic.QldSAWATas.NTACTAustralia
1828Nov.--------
18332 Sep.--------
18362 Sep.--------
18412 Mar.----27 Sep.---
1844---26 Feb.-----
18462 Mar.--26 Feb.-----
1847-----31 Dec.---
1848----10 Oct.----
18511 Mar.--1 Jan.-1 Mar.---
1854-26 Apr.(a)--30 Sep.----
1855---31 Mar.-----
18561 Mar.--------
1857-29 Mar.---31 Mar.---
1859----31 Dec.----
18617 Apr.7 Apr.7 Apr.(a)7 Apr.-7 Apr.---
1864--1 Jan.------
1866---26 Mar.-----
1868--2 Mar.------
1870----31 Mar.7 Feb.---
18712 Apr.2 Apr.1 Sep.2 Apr.-----
1876--1 May26 Mar.-----
1881(b)3 Apr.3 Apr.3 Apr.3 Apr.3 Apr.3 Apr.3 Apr.(c)-3 Apr.
1886--1 May------
18915 Apr.5 Apr.5 Apr.5 Apr.5 Apr.5 Apr.5 Apr.-5 Apr.
190131 Mar.31 Mar.31 Mar.31 Mar.31 Mar.31 Mar.31 Mar.(a)31 Mar.
  1. Included with NSW.
  2. The first simultaneous census of all Australian colonies.
  3. Included with SA for the 1866, 1871 and 1876 Censuses. The NT was transferred to the Commonwealth on 1 January 1911.

The first national Census was taken in 1911 (April 3), with further Censuses held in 1921 (April 4), 1933, 1947, 1954, and 1961 (June 30). Since 1961, Censuses have been conducted every five years. These were held on June 30 until 1986. Since 1991, Censuses have been held on August 6 (1991 and 1996), August 7 (2001), August 8 (2006), August 9 (2011 and 2016), and August 10 (2021).

Estimated resident population

Estimated resident population (ERP) is used to measure the population size. ERP was introduced following the 1981 Census with the methodological change from estimating population based on Census night location to place of usual residence. The 1976 and 1971 Census population estimates were recast using this methodology. The conceptual basis for using place of usual residence for population estimates is detailed in Information Paper: Population Concepts, 2008 and Population Estimates: Concepts, Sources and Methods, 2009. For further information on the 1981 methodological change, see Population Estimates: An Outline of the New Conceptual Basis of ABS Population Estimates, 1982.

For Census dates, ERP is derived from usual resident Census counts, estimated net Census undercount, and the estimated resident population temporarily overseas on Census night. Overseas visitors in Australia are excluded from this count. 

From the Census base, ERP is updated quarterly by adding births, deaths, and net migration.  After each Census, intercensal population estimates are revised to ensure that the total intercensal population increase over the period aligns with the difference between the adjacent Census-based ERPs.

Following the 2011 Census, ERP was recast data back to 1991. While previous ERPs changed, growth rates remained relatively consistent with previously published estimates. Unless otherwise indicated, statistics which use ERP as a denominator have also been revised back to 1991 in this publication. For further information, see Final Rebasing of Australia's Population Estimates, December Quarter 2012 and Recasting 20 Years of ERP.

Intercensal difference

Since July 1976, final intercensal difference has been recorded as a component of population change. Between July 1971 and June 1976, no intercensal difference exists due to the method used to recast estimated resident population after the 1981 Census. Prior to July 1971, intercensal difference was incorporated into the overseas and interstate migration components of population change. For further information, see Population Estimates: An Outline of the New Conceptual Basis of ABS Population Estimates, 1982.

Population distribution

Population estimates for each reference date are presented based on a consistent statistical geography, however caution must be exercised when comparing populations across time as they may be based on different boundaries. Refer to the footnotes for each table for more information about the statistical geography used in that table. For further information refer to the ABS Geography home page. 

The regions specified in this publication are Greater Capital City Statistical Areas (GCCSAs), Significant Urban Areas (SUAs), Local Government Areas (LGAs), and urban and rural areas. GCCSAs represent the socioeconomic area of each of the eight state and territory capital cities. SUAs represent concentrations of urban development with populations of 10,000 people or more. LGAs are legally designated areas over which incorporated local governments have responsibility. 

Urban and rural areas are as defined for the Census conducted on or near the reference date. In recent Censuses, urban and rural areas were based on the ABS Section of State structure, which aggregates Urban Centres and Localities on the basis of population ranges. Urban areas represent combinations of these urban centres while rural areas represent the rest of the country. Urban and rural areas were defined similarly in earlier Censuses.

Regional population estimates based on the concept of usual residence have been produced since the 1970s. Prior to this, population figures were calculated on an actual location concept. Estimates based on actual location are generally higher in areas which attract short-term migrants. This break in time series should be noted when comparing historical population estimates. For further information on regional population estimates, see Regional Population .

Births

Birth statistics are sourced from birth registration systems administered by state and territory registrars. The datasets are based upon data provided on a registration form completed by the parent(s) of the child. 

Birth statistics refer to the live births registered during the calendar year and are presented based on the state or territory of usual residence of the mother, regardless of where in Australia the birth occurred or was registered. Prior to 1969, birth data are presented based on the state or territory of the birth's registration. 

Estimated resident populations (ERPs) are used as denominators in the calculation of the fertility rates presented in this publication. 

For further information, refer to Births, Australia | Australian Bureau of Statistics (abs.gov.au)

Deaths

Registration of deaths is the responsibility of the state and territory registrars. Information about the deceased is acquired from a Death Registration form (DRF) completed by the funeral director, based on information supplied by a relative or other person acquainted with the deceased, or by an official of the institution where the death occurred. As part of the registration process, information on the cause of death is either supplied by the medical practitioner certifying the death on a Medical Certificate of Cause of Death (MCCD) or supplied as a result of a coronial investigation. This information is supplied to the ABS by individual registrars for coding and compilation into aggregate statistics. Core data items are collected in all states and territories and therefore statistics at the national level are available for key characteristics. Some states collect additional information. For further information see Deaths, Australia | Australian Bureau of Statistics (abs.gov.au)

Unless otherwise indicated, death statistics refer to deaths registered during the calendar year shown. There is usually an interval between the occurrence and registration of a death (referred to as a registration 'lag'). As a result, some deaths occurring in one year are not registered until the following year or even later. This can be caused by either a delay in the submission of a completed form to the registry, or a delay by the registry in processing the death. Deaths which occur in November and December are also likely to be registered in the following year. 

Death statistics prior to 1971 are presented based on state or territory of registration. From 1971, they are presented based on the state or territory of usual residence of the deceased, regardless of where in Australia the death occurred or was registered.  

The ABS Death Registrations collection includes all deaths that occurred and were registered in Australia, including deaths of persons whose place of usual residence was overseas. Deaths of Australian residents that occurred outside Australia may be registered by individual Registrars, but are not included in ABS death statistics. However, deaths of identified Australian diplomats while overseas are included.  

As deaths of Australian residents which took place overseas are not included in the statistics, deaths of Australian troops overseas in World War I are excluded. Similarly, Australian troops who died overseas during World War II are not included in death statistics, however they have been removed from the population estimates.

Life expectancy

Life expectancy statistics are calculated using life tables. A life table is a statistical model used to represent the mortality of a population. In its simplest form, a life table is generated from age-specific death rates and the resulting values are used to measure mortality, survivorship, and life expectancy. 

Life tables are presented separately for males and females. The life table depicts the mortality experience of a hypothetical group of newborn babies throughout their lifetime. It is based on the assumption that this group is subject to the age-specific mortality rates of the reference period. Typically, this hypothetical group is 100,000 persons in size.  

Life tables produced by the ABS since 1995 differ from those published prior to 1995 in a number of important respects:

  • They are based on three years of deaths and population data. This is intended to reduce the impact of year-to-year statistical variations, particularly at younger ages where there are small numbers of deaths, and at very old ages where the population is small. 
  • The deaths and population data are based on Australian residents who are physically present in Australia over the three-year period i.e. Australian residents temporarily overseas are excluded as are deaths in Australia of overseas visitors. 
  • They have been actuarially graduated on the same principles used for the quinquennial Australian life tables prepared by the Australian Government Actuary.
  • From 2012 a small refinement has also been made to bring Australia's mortality rates (qx values) into line with other comparable countries. For further information, see Life Expectancy | Australian Bureau of Statistics (abs.gov.au).

Survivorship rates are the proportion of the population described in life tables that survive until exact age,           \(x+1\) (\(s_x\)). These rates are calculated from life table age-specific mortality rates,  \(q_x\), which provide the probability of dying between age \(x\) and age \(x+1\). From \(q_x\), the probability of surviving between ages \(x\) and \(x+1\) (\(p_x\)) is given by \(1-q_x\). The equation to calculate survivorship at a specific age (\(s_x\)) applies the probabilistic chain rule to \(p_x\) through the equation:

\(s_{x}=p_{x}\times \left\{ p_{x-1}\times \left[p_{x-2}\times \left( \cdots \times p_{0} \right)\right]\right\}\) where,

\(s_x\) = the proportion of the population surviving until age, \(x+1\),

\(p_x\) = the probability of surviving the year \(x\) to \(x+1\),

\(p_{x-1}\) = the probability of surviving the year \(x-1\) to \(x\),

\(p_0\) = the probability of surviving the first year of life.

Overseas Arrivals and Departures (OAD)

OAD statistics include all recorded traveller movements across Australia's international border. The statistics report on the number of international border crossings rather than the number of people (i.e. multiple movements of an individual traveller during a given reference period are each counted separately). OAD statistics include the movements of all travellers regardless of their nationality, citizenship, or legal status. 

OAD statistics exclude the movements of operational air and ships' crew, transit passengers who pass through Australia but are not cleared for entry (including some defence force personnel), and passengers on cruises commencing and finishing in Australia. These statistics also exclude undocumented arrivals or departures.

Administrative data collected and compiled by the Department of Home Affairs are used to compile OAD statistics. This is done using various processing systems, visa information, passport documents, and incoming passenger cards, under the authority of the Migration Regulations (Migration Act, 1958). 

The monthly OAD publication focuses on information and analysis of short-term movements (i.e. less than one year), in particular short-term visitor arrivals (STVA) and short-term resident returns (STRR).

2017 review and break in series

Due to the removal of the Outgoing Passenger Card (OPC) by the Department of Home Affairs from 1 July 2017, the ABS undertook a review of its OAD statistics, methodology and processing systems. This provided an opportunity to consider alternative data sources and ways to make better use of a range of existing data collected by Home Affairs about Australia's international border crossings. For detailed information on the changes and improvements arising from the 2017 review of OAD statistics, see the History of changes section of Overseas Arrivals and Departures, Australia, methodology.

The review resulted in a break in series, necessitating a revised time series for OAD data from July 2007 to June 2017 based on the new methodology. Figures prior to June 2007 may not be strictly directly comparable to those which follow.

Overseas migration

Net Overseas Migration (NOM)

To estimate NOM, and thereby Australia's official estimated resident population (ERP), the ABS employs this concept of usual residence for all travellers who arrive in or depart Australia. A person arriving in Australia is added to the ERP counts if, by arriving in Australia, they are changing their country of usual residence from another country to Australia. The arrival will be counted as an overseas migrant arrival if they reside in Australia for a period of 12 months or more over a 16-month period after arriving. By the same method, a departing person changing their country of residence from Australia to another country is removed from the ERP counts as an overseas migrant departure. 

Measuring the duration of presence in Australia or overseas over a 16-month period means the 12 months does not have to be continuous. For example, a person can leave Australia for a short period after their initial arrival and still be counted as an overseas migrant arrival. For more information see the section on “The 12/16 month rule” below. 

NOM and ERP estimates include all people regardless of nationality, citizenship or legal status, who usually live in Australia, except for foreign diplomatic personnel and their families, and are based solely on duration of presence in Australia. 

Sources of overseas migration data

Each month all overseas arrivals and departures (OAD) movement records are processed by the ABS to produce OAD statistics. This processed OAD data is then used to produce quarterly NOM estimates. 

ABS statistics on overseas migration are mainly compiled using information from the Department of Home Affairs. All overseas movement records are stored on the Home Affairs' Travel and Immigration Processing System (TRIPS). 

Each month all movement records are supplied by the Department of Home Affairs to the ABS for production of the OAD estimates. From July 2017, due to the removal of the outgoing passenger card, the ABS has also used Medicare enrolment data as a secondary source of State of residence information for Australian residents.

History of methods used for calculating NOM

Due to changes in the methods used to measure overseas migration estimates, caution should be used comparing them over time. This is especially so for estimates based on permanent and long-term movements from OAD compared to those using the '12/16 month rule' method. The table below describes the various methods used in Australia that have been applied to measuring overseas migration.

Historical methods used
Reference PeriodMethod Used
Prior to 1911The difference between the total overseas arrival and departure movements(OAD) movements provided an estimate for net overseas migration
Between 1911 and June 1933The difference between the total overseas arrival and departure movements,   provided an estimate for net overseas migration, with an intercensal adjustment applied to overseas departures(a)
Dec 1933 - June 1971The difference between the total overseas arrival and departure movements provided an estimate for net overseas migration, with an intercensal adjustment applied to the net migration figure(a)
Dec 1971 - June 1976The difference between permanent and long-term arrival and departure movements from OAD were used(a)
Dec 1976 - June  1997The difference between permanent and long-term arrival and departure movements from OAD were used, with 'Category jumping' adjustments applied(b)
Sep qtr 1997 - Jun qtr 2001The difference between permanent and long-term arrival and departure movements direct from OAD were used, with n. No adjustments applied ((i.e. 'category jumping' set to zero)(c)
Sep qtr 2001 - Jun qtr 2006The difference between permanent and long-term arrival and departure movements, direct from OAD were used with Migration adjustments applied, based at the aggregate level(d)(e)
Sep qtr 2006 - Jun qtr 2021‘12/16 month rule’, based on actual duration of stay/absence, based at the individual traveller level (12/16 month rule)(f)(g)(h)(i)(j)(k)
  1. See Population Estimates in Australia: A Discussion Paper, 1979
  2. See Category jumping: trends, demographic impact and measurement issues, 2000 
  3. See Estimated resident population and measurement of category jumping, 2003 
  4. See Net overseas migration: adjusting for actual duration of stay or absence, 2003 
  5. See Measuring net overseas migration, method used September quarter 2001 to June quarter 2006 
  6. See Improved methods for estimating net overseas migration, 2006 
  7. See Statistical implications of improved methods for estimating net overseas migration, Australia, 2007 
  8. See '12/16 month rule' methodology for calculating net overseas migration from September quarter 2006 onwards
  9. See Improving net overseas migration estimates, 2010 
  10. See Further improvements to net overseas migration estimation, 2013 
  11. See Improvements to the estimation of net overseas migration, 2018 

The 12/16 month rule – from July 2006 onwards

The method used for estimating overseas migration employs the '12/16 month rule'. For the purposes of overseas migration, a person who is not already counted in the estimated resident population (ERP), is added to the ERP if they travel to Australia and remain present in Australia for 12 months or more (i.e., an overseas migrant arrival). Likewise, a person who is already counted in the ERP is removed from the population if they leave Australia for 12 months or more (i.e., an overseas migrant departure). 

The 12-month duration does not have to be continuous and is measured over a 16-month period. The person determined to have migrated, is added or removed from the ERP from the date they arrived or departed, i.e., from the beginning of the 16-month calculation period. 

To measure a traveller's actual duration of stay, arrivals and departures are sequenced to construct a traveller's movement history which is then used to measure durations of stay in and out of Australia. 
 

Permanent and long-term movements – July 1971 – June 2006

From July 1971 – June 2006, NOM estimates were based on the number of recorded permanent and long-term overseas arrivals and departures. A number of adjustments were made to these figures from July 1976 onwards.

These mainly comprised adjustments designed to reflect differences between an individual's stated travel intentions (from the passenger card) and their actual recorded travel behaviour. ‘Category jumping’ was a measure of the discrepancy between movements recorded as short-term, long-term or permanent at the time of movement, and the category recorded at the completion of a journey. In addition, adjustments were also used to transform counts of overseas movements into counts of travellers. Combined, these were referred to as 'migration adjustments'. For more information refer to footnotes (d) and (e) in the ‘Historical methods used for calculating NOM’ table above.

Net total overseas movements – prior to July 1971

Prior to July 1971, overseas migration estimates were calculated as the total number of overseas arrivals recorded minus the total number of overseas departures recorded. This gave a net total overseas movements count and was used as the migration measure prior to July 1971. 

From July 1911 – June 1933, an intercensal adjustment was applied, whereby the latest census count was accepted as the best estimate, and population figures were therefore adjusted to incorporate the discrepancies. Overseas migration was considered the least reliable component of population change at the time and the primary cause of the discrepancy, so the adjustment was applied to overseas departures.

From July 1933 – June 1971, the intercensal adjustment was applied to the net migration figure, instead of overseas departures. 

War time

During World War I, troops leaving Australia were regarded as migrant departures, while those returning were regarded as migrant arrivals. This largely explains the record loss in 1916, and a large migration gain in 1919. During World War II, troop movements between September 1939 and June 1947 were excluded from calculations of overseas migration.

Country of birth

Country of birth classifications used by the ABS and preceding statistical agencies have changed over time. Tables presented in Australian Historical Population Statistics display the country of birth classifications in existence at the time of production of the data. For more detailed information on the most recent classification of countries, refer to the ABS publication Standard Australian Classification of Countries (SACC), 2016.

Aboriginal and Torres Strait Islander population

Estimates of the Aboriginal and Torres Strait Islander population were first produced by the ABS in 1994, in Experimental Estimates of the Aboriginal and Torres Strait Islander Population, 1986 to 1991. Estimates of the Aboriginal and Torres Strait Islander population based on the 2021 Census were released in Estimates of Aboriginal and Torres Strait Islander Australians, and a time series of estimates and projections based on the 2021 Census is scheduled for release in 2024.

There are no accurate estimates of the population of Australia before European settlement. Many estimates were based on post-1788 observations of a population already reduced by introduced diseases and other factors. Smith (The Aboriginal Population of Australia (1980) by L.R. Smith, Australian National University Press for the Academy of Social Sciences in Australia, Canberra) estimated the absolute minimum pre-1788 population at 315,000. Other estimates put the figure at over one million people, while recent archaeological evidence suggests that a population of 750,000 could have been sustained.

Until 1967, section 127 of the Constitution required the exclusion of 'Aboriginal natives' from estimates of the population of Australia. 'Aboriginal natives' were interpreted as being people who had more than 50% Aboriginal 'blood'. This provision was repealed with the proclamation of the Constitution Alteration (Aboriginals) Act 1967 so that since 10 August 1967 population statistics were to officially include 'full-blooded' Aboriginal and Torres Strait Islander people. Some estimates were backdated to 1961. For further information see Population Issues, Indigenous Australians, 1996.

From the 1971 Census, Aboriginal and Torres Strait Islander persons have no longer been asked to state their degree of Aboriginal and Torres Strait Islander descent. Since this time, in 1996 for example, the Census question has asked 'Is the person of Aboriginal or Torres Strait Islander origin?'. Changing social attitudes, political developments, improvements in Census coverage and a broader definition of 'Aboriginal' and 'Torres Strait Islander' are likely to have contributed to the rapidly rising numbers of Aboriginal and Torres Strait Islander people that have been recorded since 1971. For further information on increases in Aboriginal and Torres Strait Islander population counts between Censuses, refer to Understanding change in counts of Aboriginal and Torres Strait Islander Australians: Census, 2021.

Since 1981, all ABS Aboriginal and Torres Strait Islander population statistics are based on responses to the ABS standard question for Aboriginal and Torres Strait Islander identification, which is used in self-enumerated collections. The same Census question has been used to determine Aboriginal and Torres Strait Islander status since the 1981 Census.

Accuracy and rounding

All data are affected by errors in reporting and processing. Registered births and deaths data are also affected by delays in registration. In this release, estimates and their components have sometimes been rounded. Both rounded and un-rounded figures should not be assumed to be accurate to the last digit shown, and no reliance should be placed on statistics with small values. In commentary based on the statistics in this release, it is recommended that the relevant statistics be rounded. Where figures have already been rounded, discrepancies may occur between sums of component items and totals.

Confidentiality

The Census and Statistics Act, 1905 provides the authority for the ABS to collect statistical information and requires that statistical output shall not be published or disseminated in a manner that is likely to enable the identification of a particular person or organisation. This requirement means that the ABS must take care and make assurances that any statistical information about individual respondents cannot be derived from published data.

Techniques used to guard against identification or disclosure of confidential information in statistical tables include suppression of sensitive cells and random adjustments to cells with very small values. Throughout this publication, different methods of confidentialisation have been used. In some cases, cell values have been suppressed and are not available for publication but are included in totals where applicable. In these cases, data may not sum to totals. Further information can be found on the ABS website.

Referencing these statistics

Where original sources are referred to:

  • (original source) as quoted in this publication, (year), Historical Population.

Otherwise refer to Historical Population:

  • Source: Australian Bureau of Statistics, (year), Historical Population.

Acknowledgments

ABS publications draw extensively on information provided freely by individuals, businesses, governments, and other organisations. Their continued cooperation is very much appreciated; without it, the wide range of statistics published by the ABS would not be available. Information received by the ABS is treated in strict confidence as required by the Census and Statistics Act, 1905

Glossary

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Abbreviations

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I-Notes - data cubes

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