* The "$65,000" per mile for the Warren bike route might be misleading. It's probably much, much higher than that for the separate bicycle parts and much, much less for the bike-lane-on-road parts.
* Most of the cost of building the GAP was provided by the rail road company who built the original railway the pat uses.
* Most of the cost of building the C&O path was provided by the canal company.
* How many former railways/canal routes are available to make into transportationally-useful bike paths?
* Glens Falls/Queensbury, NY are mostly suburban spawl (not exactly "rural").