Why Is the American Dream Dead in the South? - Matthew O'Brien - The Atlantic
How likely is it that a child born in the bottom 20% of the economy will rise into the top 20%? The degree of social mobility is a key indicator of the health of American society — without sufficient social mobility, we become a class-stratified society.
Overall measures of social mobility in the United States tend to disguise the fact that it varies tremendously from region to region. This map shows where social mobility is highest (pale yellow) and lowest (deep red). The first of the two links has several additional maps along with discussion of source information and methodology. The second link talks about what factors do (and do not) seem to matter in social mobility.