@Ken Mathews: Single female headed households with children do make up a large part of poverty in America, but the fault of that falls on men. We have a culture of males that eschew responsibility, rejects marriage and doesn't provide for their children. Many of these single female headed households once included a husband, but he ran off.
Poverty in America is closely associated with single female headed households. Households formed ussually as the result of the rejection of the idea that marriage should proceed sex and procreation and rejection of the idea that divorse is a tragedy that should be used only as a last resort (cases of abuse, abandonment, etc.) A household of an unmarried woman with children is far more susceptible to being among the working poor than a married couple with children.
The second cause is the effects of various progressive/socialist policies that slow economic growth and that produce economic distortions reslting in increased unemployment and underemployment.
Thanks for the article. Mr. Gingrich and others who have the potential to earn extremely well in the paid labor market forget that that makes his decision to "work" a sensible one, but for the parent who can expect only minimum wage or now, thanks to welfare to work programs, no-wage, work, his solution does not fit the reality of the poor family. We must add that caring for children is also work, it is just unpaid work. So the observation I would like to add is that both your article and Mr. Blow's define work as paid market work, which is a male-oriented definition that devalues the skills and effort needed to care for children (and increasingly, aging adults or disabled returning veterans). The poor often will attempt to have at least one parent doing this work, since subsidized child care is essentially of dubious quality--note the many tragic deaths that have occurred of children left with paid caregivers. Many parents doubt that they can replace their own care without harming their children in one way or another. Consequently, I think a relevant element to add to your discussion is, "Is the slight increase in income from having a poor parent go into the paid labor market worth it in the cost benefit analysis for the family unit? If a woman snags a minimum wage job 40 hours, she'll make $280 a week before taxes. The additional expense of dressing for success and to pay for transport and food will dissolve that entire paycheck. Perhaps, as Robert Theobald famously said in Toward Full Unemployment, her worth to the nation is greater as caregiver to her own children than it is as a low grade (paid) worker.
Another reason why people work less than full time is that such a large proportion of the jobs out there -- food service, retail, etc. -- do not offer 40 hours per week to the majority of their employees. It is very common to be offered 29 hours so that you don't qualify for benefits, particularly health insurance. 29 (or 34) hours is a lot better than nothing, but it makes it look to ecconomists as if you're slacking.