Thanks, Fritz. I would interested in seeing the text - could you post it here?
As I understand it, this idea originated in the New Mexico Capitol, either in the Governor's office or in the Attorney General's office - I don't remember. The hope is that by creating this new designation (there is no existing "national scenic railroad") it opens up new avenues for federal funding, for example possibly from the National Park Service.
The Congress has done this before, just not for a railroad. The New River in NC/VA/WV was the first National Scenic River, for example.
JAC