Brief history of the labor aspect of May Day in North America:
In 1884, unions declared that eight hours would constitute a legal day’s work from and after May 1, 1886.
In support workers went on strike at a factory in Chicago on May 3, 1886, police fired into the peacefully assembled crowd, killing four and wounding many others. The workers movement called for a mass rally the next day in Haymarket Square to protest this brutality.
The rally proceeded peacefully until the end when 180 police officers entered the square and ordered the crowd to disperse. At that point, someone threw a bomb, killing one police officer and wounding 70 others.
The police responded by firing into the crowd, killing one and injuring many others.
Eight of the city’s most active unionists were charged with conspiracy to commit murder even though only one was present, on the speakers’ platform. All eight were found guilty and sentenced to death, despite a lack of evidence connecting them to the person who threw the bomb.
Four were hanged on November 11, 1887, Louis Lingg committed suicide in prison, and the remaining three were finally pardoned in 1893.
Lucy Parsons, the widow of Albert Parsons, traveled the world urging workers to celebrate May Day and to remember the events of Haymarket and the subsequent government-sponsored murder of those fighting for the rights of all workers.
Over time, May Day grew to become an important day for organizing and unifying the international struggle of workers and their allies.