Just watched this about the history of the rail-to-trails movement:

https://www.pbs.org/video/from-rails-to-trails-Qj9S1f/

Good piece, despite a couple inaccuracies/oversimplifications. 1. Reversion does not always happen upon abandonment. Many roads have fee ownership of parcels. 2. Not all property owned by railroads was given to them by the federal government. That is particularly true in the NE, where "Farmer Brown et ux." often received good money from the acquiring road for a strip of land.