The eight-hour workday is officially started on the 5^th January, 1914 with the Ford Motor Company announces an eight-hour workday and minimum daily wage of $5 in salary plus bonuses.

The eight-hour day movement or 40-hour week movement, also known as the short-time movement, was a social movement to regulate the length of a working day, preventing excesses and abuses.

Source: 5th Day of January – Fatcowco