From the New York Times:
In a large, continuing study of upward mobility based at Harvard, commuting time has emerged as the single strongest factor in the odds of escaping poverty. The longer an average commute in a given county, the worse the chances of low-income families there moving up the ladder.
The relationship between transportation and social mobility is stronger than that between mobility and several other factors, like crime, elementary-school test scores or the percentage of two-parent families in a community, said Nathaniel Hendren, a Harvard economist and one of the researchers on the study.
A separate report focusing on New York, from New York University’s Rudin Center for Transportation, came to a similar conclusion. The study compared neighborhoods by accessibility to mass transit and the number of jobs within an hour’s commute. It found that residents of the areas least well served by mass transit relied on personal vehicles. Areas in the middle third — those with some, but insufficient, access to transportation — had the highest rates of unemployment and the lowest incomes, the study found.