In Climbing Income Ladder, Location Matters – NYTimes.com.
All else being equal, upward mobility tended to be higher in metropolitan areas where poor families were more dispersed among mixed-income neighborhoods. Income mobility was also higher in areas with more two-parent households, better elementary schools and high schools, and more civic engagement, including membership in religious and community groups.
Hey wait that cuts across party lines what should I believe?! Cf. The Geography of Stuck.