On May 1, 1886, roughly 300,000 to 500,000 workers across the United States went on strike to demand an eight-hour workday, with Chicago as the movement's epicenter. The demonstrations were largely peaceful, but tensions escalated days later at Haymarket Square, where a bomb killed police officers and bystanders. The date was later adopted internationally as May Day, a global holiday honoring labor.
Chicago in 1886 was a city bristling with industrial ambition and immigrant labor, and on the first of May tens of thousands poured into its streets carrying banners reading 'Eight Hours for Work, Eight Hours for Rest, Eight Hours for What We Will.' The Knights of Labor and various trade unions had spent months organizing what became, at the time, the largest simultaneous strike action in American history.
The May 1 demonstrations themselves passed without major violence, but the atmosphere they created led directly to the Haymarket affair three days later, when someone threw a bomb during a labor rally, killing a police officer and triggering a chaotic gunfight. Eight anarchists were controversially convicted despite scant evidence linking most of them to the bombing; four were hanged.
The global labor movement, seeking to honor the Chicago martyrs and the original demand for shorter hours, designated May 1 as International Workers' Day in 1889. Ironically, the holiday is celebrated with parades and speeches across dozens of countries today, yet remains largely uncelebrated in the United States where it began.