Quote: "So what does constitute a historic railway?"
Depends on where you are. LOL
The history of Colorado is only about 150 years old, and any train ride through beautiful country on original railbed is "historic".
Wouldn't it be neat to ride the DSP&P line up Chalk Creek Canyon to Hancock and the tunnel? Wouldn't we all like to ride from the west side of the tunnel down to Pitkin? Or how about a ride on the Shortline from Colorado Springs to Cripple Creek? We can in our cars, but still riding on rails behind an engine (preferably steam) is better in our minds.
Riding through the Royal Gorge is "historic" only in the fact that you are on a passenger train. The cars aren't painted in the original colors but that doesn't matter. To those people that remember riding troop trains through there it's the ride, not what they're riding in.
I wish the RGRR was in operation when my dad was alive as he would have throughly enjoyed riding it. It would have brought back old WWII memories and stories that he could have shared with his grandkids. That's the "heritage".