Friedersdorf traces them:

In 1912, Massachusetts enacted America’s first minimum wage law, but it only applied to women and children. Unlike men, they were deemed weak, and in need of protection from employers. As an empirical matter, their wages were much lower and their working conditions more dismal. There was also social unease with the increasing number of unmarried women working and living alone in the city — if their wages didn’t provide for their sustenance, who knew how they might make ends meet? A woman ought to be allowed to forgo marriage and pursue work outside the home, an article in The Literary Digest conceded, but she must become sufficiently skilled to earn a living wage, “because she has given to society the equivalent of that which she expects in return.” Otherwise, she ought to stay in her father’s house. Yet “if she has been driven into industry, not because she deems it her vocation to lie therein, but because her father can not support her at home, she is, indeed, the victim of our bad economic system, which has so nearly broken down…. She it is that is in greatest danger of falling into prostitution.”