A new study was just released that is considered the most detailed study of income mobility yet. One of their most significant findings:
Finally, some of the strongest predictors of upward mobility are correlates of social capital and family structure. For instance, high upward mobility areas tended to have higher fractions of religious individuals and fewer children raised by single parents
Unlike most studies that are released, the authors were kind enough to be honest with their results:
We caution that all of the findings in this study are correlational and cannot be interpreted as causal effects.
What is factual is that many areas in the southeast of the United States show very little upward mobility including the large metropolitan areas of Atlanta and Charlotte:
You can play with the interactive map on the New York Times website.