May Day demonstrations would last several days in 1866, in Milwaukee, Wisconsin, on the Lake Michigan shore, ancestral homeland of the Potawatomi and Ho-Chunk.

Workers march and demand formalization of an eight-hour work day. Strikers manage to close nearly every business and industry in town, from bakeries to breweries. State militia are called in.

On the morning of May 5, at least 1500 marchers — including children — approach North Chicago Rolling Mills, the largest factory in town and the only one still operating, to rally workers there to join the strike. The militia commands them to stop, but whether or not these orders are heard, the march does not stop. The militia is commanded to fire upon the crowd. Seven people die, including a thirteen-year-old boy.