There shall be a system of state highways in the state, a system of county highways in each county, a system of highways in each highway district, and a system of highways in each city, except as otherwise provided. The improvement of highways and highway systems is hereby declared to be the established and permanent policy of the state of Idaho, and the duty is hereby imposed upon the state, and all counties, cities, and highway districts in the state, to improve and maintain the highways within their respective jurisdiction as hereinafter defined, within the limits of the funds available.
Idaho Code § 40-201