The first May Day was celebrated in 1886, with a general strike of three hundred thousand workers at thirteen thousand businesses across the United States. It was a tremendous show of force for the American labor movement, which was among the most militant in the world.

Many of the striking workers — who numbered forty thousand in Chicago alone — rallied under the banners of anarchist and socialist organizations. Trade unionists from a variety of ethnic backgrounds — many of them recent immigrants — marched shoulder-to-shoulder, making a unified demand for the eight-hour day.

The movement to limit the workday posed a significant threat to American industrialists, who were accustomed to demanding much longer hours from their workers.