This is a problem that a lot of cities -- not just in the US -- will have to solve sooner rather than later. People are willing to move out of the city if there is a viable and reasonable way of commuting to work. My family and I moved to the suburbs because it was cheaper and better for the kids. The trade-off was that our commute went from 30 minutes to 2 hours. That was 10 years ago. These days, if we drive to work, it'll take us 3 to 4 hours so we just take the train.