A recent study shows that social mobility was never has high in the U.S. as perceived, but, on the other hand, mobility has not declined in most states, contrary to common belief. Instead, declining mobility is concentrated among a cluster of states in the U.S. South. This sort of empirical analysis is crucial to sorting out the realities of social and economic inequality in America and devising effective responses.
For example, one thing the study highlights is that low-income children raised in stable, two-parent households have a better chance of upward social mobility. Marriage rates are low among low-income black households; i.e., many single moms. Some people use such data to condemn young black males as poor fathers. Other data, however, show that a big reason black males are not present is that our radicalized system of mass incarceration ensnares a high percentage of young black males, locking them up for long periods in prison, stunting their educational opportunities, limiting their employment prospects after prison and rendering them unable to sustain stable long-term family commitments. As Michelle Alexander demonstrates, this is not because black males are more likely to commit crimes than their white counterparts at similar socio-economic levels, but because of the discriminatory ways in which drug laws (and sentencing) are used to target minority youth. Ditch the drug war and reform the criminal justice system, and one would see major changes (for the better) in rates of marriage and family stability. Leading to greater social mobility, etc. etc. Finally, politicians are waking up to the need for reforms to the criminal justice system, including sentencing (here, here, here).