Abstract

Census counts of Aboriginal and Torres Strait Islander peoples in Australia increased from 455,000 in 2006 to 813,000 in 2021, substantially exceeding growth in the non-Indigenous population. We examined how demographic change, identification dynamics, Census operations, mobility and geography, and governance contribute to this variation. Aggregate Australian Bureau of Statistics Census TableBuilder data for 2006-2021 were analysed alongside a PRISMA-aligned rapid literature review from 1990 to 2025. The Indigenous Census count increased 79% over the study period. The population with Indigenous status recorded as ‘not stated’ exceeded the Indigenous count in every Census and varied markedly between cycles. Published ABS decomposition estimates indicate that non-demographic factors accounted for 38.7% of intercensal growth in 2006-2011, 39.0% in 2011-2016 and 56.5% in 2016-2021. Nearly one-third of non-demographic change in 2016-2021 occurred among children aged 5-14 years. The review identified four interacting non-demographic domains: identity and reporting, Census operations and processing, mobility and population geography, and governance and interpretation. Historical and structural contexts were cross-cutting. Variation in Indigenous Census counts cannot therefore be interpreted as demographic change alone. Strengthening Indigenous population measurement requires transparent documentation of Census processes, explicit treatment of missing status, careful rate interpretation, and Indigenous-led governance in official statistics.