1886
The general strike for the eight-hour day
Between 300,000 and 500,000 workers strike in the United States for the eight-hour day, up to 40,000 in Chicago alone. On May 4, a bomb in Haymarket Square kills police officers and civilians, and four anarchists are hanged in 1887. In 1889, May 1 becomes Workers' Day in memory of Chicago.
Source: Wikipedia, Haymarket affair
