For many, Labor Day weekend signals the end of summer and an opportunity to host a barbecue. But this national holiday—celebrated every year in the United States and Canada on the first Monday in September—has revolutionary origins.

Originally commemorated through parades, political speeches, and labor union activities, Labor Day was born amid rising unrest over oppressive working conditions—and a massive strike that threatened to turn violent.

By the late 19th century, the Industrial Revolution had made working life miserable for people around the world. In many places, workers toiled for at least 12 hours a day six days a week in mines, factories, railroads, and mills. Children were especially exploited as cheap laborers who were less likely to strike. Sweatshops