While I can’t speak for other areas, the unused track around here doesn’t go anywhere useful.
Most of the unused track goes to empty, century-old factory buildings and past subdivisions that were once farms. The track next to the subdivisions was used to move grain to market — grain that is no longer being grown on what are now single family lots.
Some of the tracks were from the interurban commuter rail system, a line that was obsolete in the 1950’s and failed after a catastrophic crash that killed many people.
Beyond that, the old lines would have to be completely rebuilt to carry trains. The rails are old, the ties are rotted and the roadbed isn’t secure.
Rebuilding a rail system in the US to move people and cargo off the highways would require massive use of eminent domain, huge expenditures and restrictive zoning laws to prevent development in areas away from rail service.
What makes sense is to build a true high-speed railroad from DC to Boston in the Northeast sector. We will be able to get a lot of people off the roads, and people will be able to arrive in NYC from DC in just three hours, which will raise our productivity in the United States and reduce our congested highways while alleviating the strain on our busiest airports.