Idaho Statutes Title 49. Motor Vehicles § 49-1421. Driving on divided highways--Restricted access

(1) Whenever any highway has been divided into two (2) or more traffic lanes by leaving an intervening space or by a physical barrier or a clearly indicated dividing section so constructed as to impede vehicular traffic, every vehicle shall be driven only upon the right-hand traffic lane unless directed or permitted to use another traffic lane by traffic control devices or peace officers. No vehicle shall be driven over, across or within any dividing space, barrier or section, except through an opening in the physical barrier, dividing section or space or at a crossover or intersection as established, unless specifically prohibited by public authority.

(2) No person shall drive a vehicle onto or from any controlled access highway except at entrances and exits as are established by proper authority.