Yep. Look at something like the Michelson Trail in South Dakota. IIRC, it took some 10 years (if not more) to complete that 109 mile, mostly unpaved trail, and that was with strong state support. Cost a hell of a lot of money and is managed by a state agency. Much of the labor required to rehab the countless bridges that are part of the trail was donated by the state's National Guard. There are other, longer trails like the Cowboy Trail in Nebraska that have been around for longer and are still not fully completed.


As for maintenance, the Mickelson charges a use fee (for anyone 12 and older) for the sections outside the few municipalities it passes through. $4/day or $15 for a yearly pass. Still, I believe some trail maintenance is performed by volunteers. When I rode it in 2015 there was an older gentleman grading a section with what looked to be a private tractor.