You need to pick your sources a little more carefully. I'm always annoyed at the invocation of the logical fallacy that the source of an argument renders it in

You need to pick your sources a little more carefully. I'm always annoyed at the invocation of the logical fallacy that the source of an argument renders it inadmissible. Not only is it a fallacy, but it's typically (but not in your case, especially since you're offering a specific criticism!) invoked by someone simply assuming that their own source is sacrosanct. That said... You may have a point, but it's not fatal to my argument. It maybe renders mine less strong. Why would you think that women entering the workforce must be treated exogenously? I think it's proper to consider this part of the overall improvement. For the years shown in my chart, the shift of women into the workforce was well underway. Even in 1950, women accounted for about 30% of the workforce [1]. So by my thumbnail estimation, the increase from ~1965 (when my original chart began) on is nowhere near large enough to account for the effect I showed. Further, women entering the workforce is central to my second point about it finding oneself in the lower income tiers is significantly a personal choice. If the rest of the world has passed you by, it's still your own choices that are holding your back. Without making any moral claims at all, purely based on mathematics, the two-income family has advantages beyond simply having double the income. As I alluded to, by sharing tasks and specializing within the family (e.g., I cook while my wife does the laundry), we're able to lower total expenses because we save enough time between us that more can be done without outsourcing work. It also offers better risk management. One partner can pursue a riskier but potentially more lucrative job, without fearing losing the family's only income. I have several friends doing this kind of thing, with one spouse running a small business while the other has a corporate job (including the medical care it implies). And if one spouse does lose their income, the consequences are much less dire, as there's some semblance of a buffer protecting them. Thus, even aside from the simple doubling of family income as women entered the workplace, they shifted the picture so that more wealth could be created in total by protecting against greater risks. But this is all endogenous to the question. Through their own means (in many cases, that being the decision of a woman to enter the workforce), Americans have transformed their demographics such that incomes have shifted strongly toward the higher end of the scale. [1] http://www.bls.gov/opub/mlr/2002/05/art2full.pdf http://www.bls.gov/opub/mlr/2002/05/art2full.pdf page 2 (PDF warning) EDIT: I'd stupidly left the parens in para 4 empty; went back to fill them in.