Summary: On 21 April 1856, Australian stonemasons in Victoria undertook a mass stoppage as part of the eight-hour workday movement. It became a yearly commemoration, inspiring American workers to have their first stoppage. 1 May was chosen to be International Workers' Day to commemorate the 1886 Haymarket affair in Chicago. Thus by 1887 in North America, Labourer's Day was an established, official holiday but in September, not on 1 May.
