Idaho Code § 49-209: Local traffic-control devices.

Local authorities in their respective jurisdictions shall place and maintain traffic-control devices upon highways under their jurisdiction as they may deem necessary to indicate and to carry out the provisions of this title, or local traffic ordinances, or to regulate, warn or guide traffic. All traffic-control devices erected shall conform to the state manual and specifications referred to in section 49-201, Idaho Code; provided, however, that any offense created hereunder shall constitute an infraction as the same is defined in section 49-3401(3), Idaho Code.