In 1889, the International Socialist Conference declared May 1st an international holiday for labor in commemoration of the 1886 Haymarket affair, where police killed at least eight workers at a Chicago labor demonstration. The first of May is a public holiday in 66 countries and is unofficially celebrated in many more.
Though often associated with workers' rights, May Day also serves as a platform for fringes of the political spectrum to self-advocate—today in Germany, leftists and anarchists march in Berlin and neo-Nazis march in Erfurt.
Boeing workers in Washington State have been unionized for decades; their counterparts in South Carolina recently voted out the union in a landslide. Pacific Standard compares conditions in both workplaces, a year after South Carolina's historic vote.