Prior action of boards purporting to accept the grant of rights-of-way under section 2477 of the Revised Statutes of the United States for the construction of public highways over public lands of the United States, as provided in RCW 36.85.030, is hereby approved, ratified and confirmed and all such public highways shall be deemed duly laid out county roads and boards of county commissioners may at any time by recorded resolution cause any of such county roads to be opened and improved for public travel.