I think it goes like this:
Vermont distinguishes between ATVs and Motorcycles, and motorcycles are generally prohibited on ATV trails. ATVs are themselves prohibited on much state land, but street-legal, plated motorcycles are not, so long as you're on a road. (The definition of a road is fairly loose.)
NH requires a sticker for both ATVs and Motorcycles on OHV trials, although motorcycles are still prohibited in some areas.
Dockingpilot explained Maine.
Originally Posted by levain
Is it valid on motorcycles? I thought it was only ATV's