May 1 as a holiday for workers began in the United States. That’s right, the United States. It was born in, and commemorated, the struggle for the eight hour work day.
In the late 1800’s the union that became the AFL, along with anarchist organizers, were pushing hard for an eight hour work week. Strikes ensued. In 1886, police fired into a crowd, killing a striker. Workers protested the next day at Haymarket Square in Chicago. At the end of the rally, a bomb went off. Anarchists were blamed, several were tried in a kangaroo court and hung. In 1893, the governor pardoned all of them, saying they were innocent.
The unions went on to win the battle for the eight hour day, even though some paid with their lives.
When other countries began celebrating May Day, it took on a socialist flavor, so the U.S. changed the date here to Labor Day. Thus, most don’t even know the International Workers Day started in the U.S.