The United Kingdom Census 1921 was a census of the United Kingdom of Great Britain and Ireland that was carried out on 19 June 1921. It was postponed for two months from April due to industrial unrest and no census was taken in Ireland due to the Irish War of Independence. It was the first census in the UK to ask about place of work and industry, and whether a marriage had been dissolved by divorce.
According to the preliminary general results of the census, the population of Great Britain on 19 June 1921 was 
England and Wales
- 49,701 Jersey
- 40,519 Guernsey and others
Isle of Man
The census of Ireland was not taken until 1926, and the result was a total population of 4,228,553  divided as
- Northern Ireland...1,256,561
- Irish Free State.....2,971,992
In the 1911 census, the population of what was to become the Irish Free State had been counted as 3,139,688 
On 27 February 2019, FindMyPast announced that they had been awarded the contract by the UK National Archives (in association with the Office for National Statistics) to digitise and publish the 1921 Census online, which will be available for their subscribers from 1 January 2022.
- Employment details:
- Householders' place of employment
- The industry they worked in
- The materials they worked with
- Their employer's name.
- If aged 15 or older, marital status (including if divorced)
- If aged under 15, whether both parents were alive or if either or both had died.
- Detailed questions on education
- Niall Cullen (27 February 2019). "The 1921 Census is Coming to Findmypast". FindMyPast. Retrieved 28 February 2019.
- "Table Y.— Census Populations, 1921, British Empire, Dominions, Colonies and Possessions", in The Registrar-General's Statistical Review of England and Wales, Part 2 (Great Britain General Register Office, 1927) p.117
- "Life in 1916 Ireland: Stories from statistics"
- How to look for Census records. The National Archives. Retrieved 6 July 2017.
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