If you use Google Maps to look at location of railroad tracks, you probably already know that the owners of those tracks (i.e. the railroad name) are not identified on Google Maps.
And where the tracks have been removed, the 'map' often no longer shows the tracks, although one may be able to see the ROW using the aerial map view.
So this is an interesting project ...
Mapping Traces of Abandoned Railroads
By no means are all
abandoned railroads on the map, but an interesting feature is that the railroad that previously owned the abandoned tracks are identified on the map. For instance, here is the Butte County Railroad (SP branch) in California:
More on that branch: [en.wikipedia.org
And yes, at least parts of the NWP are on the map. ;>)