Idaho Code § 40-1302: County division or change in boundaries — Joint highway district formed.

When a county division or change in the boundaries of a county divides an existing highway district the district shall continue as a joint highway district until changed as provided by this title. It shall be the duty of the commissioners of the respective counties affected to rename the district as a joint highway district, and the renamed joint highway district shall in all things be considered a continuation of the existing district.