The push for an eight-hour workday gained momentum in the United States during the late 19th century, fueled by the industrial revolution and the rise of labor organizations. Workers faced grueling hours in hazardous conditions, and labor unions began organizing efforts to demand shorter workdays. May 1, 1886, saw a coordinated effort where thousands of laborers across various cities participated in rallies demanding an eight-hour workday. Notable events included a significant demonstration in Chicago, which was part of a burgeoning labor movement advocating for workers' rights and better working conditions.

The Chicago rally attracted a diverse group of participants, including socialists, anarchists, and labor activists. Albert Parsons, a key figure in the movement, emerged as a leader of the demonstrations. Despite the peaceful intention of the rallies, tensions mounted, culminating in the Haymarket affair. On May 4, during a demonstration at Haymarket Square, a bomb was thrown at police officers, resulting in chaos and violence. The police retaliated, leading to several deaths and numerous injuries.

The aftermath of the Haymarket affair had far-reaching implications for the labor movement in America. Strikes and protests increased in the years following, and the event highlighted the struggle between labor groups and authorities. Additionally, the fair labor practices that emerged as a result of these movements laid the groundwork for future labor laws and labor day observances. To commemorate these events and the fight for workers’ rights, May 1 became recognized as International Workers' Day in many countries worldwide, celebrating labor and social movements and honoring the contributions of working people.