You need to redesign American cities. The most obvious thing to change is zoning laws. Residential areas, offices and stores need to be more mixed.
Another issue is that many problems exist simply because it is too easy to drive. With easy driving you end up with donut cities where anything of importance is located in a ring around the outskirts of the city. That kills the ability to utilize public transport effectively.
If you discouraged driving more activity would be forced into neighborhoods and into the downtown area, which would make public transport functional. It is much easier to feed people with public transport into a downtown area than into a ring on the outskirts.