In the late 1800s, workers in parts of the US began campaigning against harsh working conditions.
Back then, 16-hour days in unsafe environments were common.
In May 1886, huge strikes gripped the city of Chicago.
Thousands of workers took to the streets to demand an 8-hour working day.
Protests were repressed by police in what became known as the Haymarket Affair.
7 union leaders were convicted of conspiracy. 4 were later executed.
The Haymarket Affair marked the start of a shift in labour relations in the US.
The 8-hour day was adopted in the printing, construction and railway industries in the early 1900s.
It eventually became law across the US in 1937.
May 1st is now a national holiday in 66 countries.
It’s a day to remember the struggles for dignity and justice at work that have gone before.
And that the fight to improve the lives of working people continues today.