The official poverty line, as I wrote yesterday, is a dated and crude statistical concept that in many ways fails to capture America's historical success at fighting economic need. It was based on the cost of food in 1963, mostly because the Department of Agriculture had some idea of what a basic grocery budget should look like, whereas there wasn't any real agreement on what families needed to spend on other essentials. Since then, it's mostly just been adjusted for inflation.
Keep that history in mind while reading this passage, which I found in a 1992 report by the Social Security Administration on how the poverty threshold came to be:
When the hypothetical family cut back its food expenditures to the point where they equaled the cost of the economy food plan (or the low cost food plan) for a family of that size, the family would have reached the point at which its food expenditures were minimal but adequate, assuming that "the housewife will be a careful shopper, a skillful cook, and a good manager who will prepare all the family's meals at home.” (bold added)
I doubt that the decline of full-time housewives slaving over their stoves has warped our poverty statistics all too terribly, given that food is now less of a concern for low-income families than healthcare or paying rent. Also, it should be noted that the economist who developed the poverty threshold used somewhat different methods for one and two-person households. What I think this passage shows, however, is that when we try to capture abstract concepts like "poverty" in a statistic, we inevitably end up wrapping a certain set of values and social expectations into the package, which can then become very outdated. As we dwell on America's successes or failures fighting poverty 50 years after Lyndon Johnson declared war on it, remember that the stats we use in that conversation are almost never as simple or straightforward as they seem.