The Eight Hour Day

From Workday Minnesota:

September 3, 1916 - Railroad workers won the eight-hour day. The legislation, called the Adamson Act, marked the first time a group of private sector workers had their working hours regulated by the federal government. It was one of many reforms pushed by the progressive movement of the early 20th century.

The Adamson Act, passed in 1916, provided workers with an eight hour day, at the same daily wage they had received previously for a ten hour day, and required time and a half for overtime. -Wikipedia