The Census Act 1800 also known as the Population Act 1800 (citation 41 Geo. III c.15) was an Act of the Parliament of Great Britain which enabled the first Census of England, Scotland and Wales to be undertaken. The census was carried out in 1801 and has been repeated almost every ten years thereafter. The 1801 census estimated the population of England and Wales to be 8.9 million, and that of Scotland was 1.6 million. Ireland was not included in the census until 1821.