My question involves an easement in the state of: Michigan
There's a line on "most" maps that extends beyond the end of a Michigan certified county road, across multiple pieces of private property, through a state forest, to a boat landing (built by the DNR) on a lake, and then terminates at a two or more different pieces of private property. On the ground it's cleared about 10 feet wide, covered in smooth packed dirt, and smooth enough to traverse in a sedan. It sure looks like a road. Between 1966 and 1969, the DNR attempted to obtain easements across the pieces of private property to guarantee access to the lake and boat landing. One property owner declined to grant an easement, so the "road" was not added to the state forest road system. One or more private property owners put "no trespassing" signs on trees in the vicinity of the dirt passageway but did not erect gates or otherwise block access. It has obviously been well-used since then, and I don't know how long prior to 1966 it was in use as a road as well.
I do not own nor do I intend to buy any of the pieces of property mentioned. My primary interest is riding on it with my ATV without encountering an angry landowner. It is legal to do so on county roads and state forest roads in the area in question.
Does the county road commission or Michigan DNR have to sue the landowners that have not blocked the road in order for it to enter public ownership as a county seasonal road or some other form of state forest road? I could approach each landowner and seek an easement for public ATV use, but if there's a ticking clock on generally opening it to the public after 50 years of unobstructed public use, I may just revisit this in 2019.

