<P> During the 1870s, eight hours became a central demand, especially among labour organisers, with a network of Eight - Hour Leagues which held rallies and parades . A hundred thousand workers in New York City struck and won the eight - hour day in 1872, mostly for building trades workers . In Chicago, Albert Parsons became recording secretary of the Chicago Eight - Hour League in 1878, and was appointed a member of a national eight - hour committee in 1880 . </P> <P> At its convention in Chicago in 1884, the Federation of Organized Trades and Labor Unions resolved that "eight hours shall constitute a legal day's labour from and after May 1, 1886, and that we recommend to labour organisations throughout this jurisdiction that they so direct their laws as to conform to this resolution by the time named ." </P> <P> The leadership of the Knights of Labor, under Terence V. Powderly, rejected appeals to join the movement as a whole, but many local Knights assemblies joined the strike call including Chicago, Cincinnati and Milwaukee . On 1 May 1886, Albert Parsons, head of the Chicago Knights of Labor, with his wife Lucy Parsons and two children, led 80,000 people down Michigan Avenue, Chicago, in what is regarded as the first modern May Day Parade, with the cry, "Eight - hour day with no cut in pay ." In support of the eight - hour day . In the next few days they were joined nationwide by 350,000 workers who went on strike at 1,200 factories, including 70,000 in Chicago, 45,000 in New York, 32,000 in Cincinnati, and additional thousands in other cities . Some workers gained shorter hours (eight or nine) with no reduction in pay; others accepted pay cuts with the reduction in hours . </P> <P> On 3 May 1886, August Spies, editor of the Arbeiter - Zeitung (Workers Newspaper), spoke at a meeting of 6,000 workers, and afterwards many of them moved down the street to harass strikebreakers at the McCormick plant in Chicago . The police arrived, opened fire, and killed four people, wounding many more . At a subsequent rally on 4 May to protest this violence, a bomb exploded at the Haymarket Square . Hundreds of labour activists were rounded up and the prominent labour leaders arrested, tried, convicted, and executed giving the movement its first martyrs . On 26 June 1893 Illinois Governor John Peter Altgeld set the remaining leader free, and granted full pardons to all those tried claiming they were innocent of the crime for which they had been tried and the hanged men had been the victims of "hysteria, packed juries and a biased judge". </P>

Where does the 8 hour work day come from