Chicago’s 1886 Haymarket affair became an international symbol of the labor movement linked to May Day.
The event began as a workers’ meeting in Chicago’s Haymarket area on May 4, 1886. Participants were protesting the killing and wounding of striking workers during an earlier confrontation at the McCormick Harvesting Machine Company.
During the meeting, a bomb was thrown at police, and gunfire followed. Police officers and civilians died or were injured. Several anarchist labor activists were arrested and prosecuted, although the evidence and fairness of the trial became subjects of lasting controversy.
The affair helped inspire international demonstrations for workers’ rights and the eight-hour day. It is often confused with the later U.S. Labor Day holiday, but Haymarket is more directly connected with May 1, International Workers’ Day.