Idaho Code § 40-616
Commissioners and boards of commissioners of any highway district are empowered to set apart on and along any public highway outside the boundaries of incorporated cities a strip of land not exceeding eight (8) feet in width for a sidewalk or side path and to make an order designating the width of the path and to cause the line separating the path from the highway proper to be located and marked with stakes, posts, grade, or other marker, unless the governing board makes a written finding supporting the public necessity for a sidewalk or side path of greater width. After the sidewalks and paths have been set apart and the line separating them from the highway has been located and marked, the use shall be restricted to pedestrians, riders of bicycles, and riders of electric-assisted bicycles, if not otherwise prohibited by local ordinance or by signage posted by the public agency with jurisdiction after notice by inclusion on a governing board agenda.
Idaho Code § 40-616