The trade union and labour movements gained momentum along with the industrial revolution. Since late 19th century, different days were being chosen by workers to celebrate labour. International Workers' Day or Labour Day, is a celebration of labourers and the working classes. The day emerged as part of international labour movement.
May 1 was officially chosen as the International Workers' Day by the Second International in 1891, to memorize the Haymarket affair that occurred in Chicago on 4 May 1886. Second International was an organization of socialist and communist parties and trade unions. It was formed in Paris on 14 July 1889 and existed till 1916.
Haymarket affair has a significant place in labour movements. There were no specific rules or regulations on the working conditions or working time during the period of industrial revolution. Workers were always at the mercy of employers and were subjected to tortures. On May 1 1886 around 20,000 U S workers started a nationwide strike demanding an eight hour workday. On May 3, the strike at the McCormick Reaper plant in Chiocago city witnessed some untoward incidents. On May 4, a crowd of around 3,000 persons was conducting a peaceful meeting in Haymarket Square. Police too were present. As the police were trying to disperse the gathering, an unidentified person threw a bomb at the police, wounding around 67 policemen. Police firing in response to the attack resulted in the killing of four demonstrators. On May 5, another seven demonstrators were killed in police firing in Milwaukee Wisconsin.
The International Socialist Congress held in 1904, in Amsterdam 1904 demanded all proletarian organisations of all countries to stop work on 1 May and demonstrate for the eight hour workday. Since then the day has witnessed work force parades and demonstrations by various socialist and communist trade unions.
In 1955, the Catholic Church declared 1 May as the day of "Saint Joseph the Worker". Saint Joseph is the patron saint of employees and craftsmen, among others. During cold war, Soviet Union used the day as an occasion to exhibit their military strength. Today, Labor Day on May 1 is observed by the majority of countries; though the U.S. celebrates its official Labor Day in September.