The gender wage gap has been in existence at least since the U.S. Civil War era, when an 1869 letter to The New York Times exposed unfair treatment of women working in government and argued that “equal work should command equal pay without regard to the sex of the laborer.” Fast forward 156 years and women still only earn 83 cents for every dollar that men make, a number that has barely budged over the past two decades and is consistent across OECD countries.