A woman punches a time clock at work in the 1960s.
New York CNN  — 

US work culture revolves around employees putting in eight hours a day, five days a week — a schedule immortalized by Dolly Parton in her 1980 song “9 to 5.”

It’s just the norm, many assume. Same as it ever was.

Except, it wasn’t always so. It has just held steady at that level since World War II.

How the United States landed on the eight-hour standard wasn’t the result of one union or one indust