As Elizabeth Warren and Amelia Tyagi have shown, ... most of the extra income earned by families as a result of the move to two-earner couples was consumed by higher housing prices as these families sought to buy homes in safer neighborhoods with better schools. (66)
Buying for better schools is a rational knowledge-class investment, and safer neighborhoods is a rational choice for every class.
If the cheaper places to live can make their schools better, then smart, able couples will move there. This would have the double benefit to the families of getting better schools for less, and allowing the couple (mostly the mothers) to cut back on work and invest the time in a happier life for the whole family.