"The latest research on social mobility showed that there's a large aggregate decline in the U.S. in your chances of earning more than your parents. But I think where the story becomes more optimistic one is that there are pockets of America, where children from low-income families have significant chances of rising up in the income distribution. This finding of big geographic variation is an encouraging one because it shows that there are places where we see the American Dream thriving and we simply need to understand how can we replicate those successes elsewhere throughout the country."