Idaho Code § 40-320: State highway construction and right-of-way costs borne by state — Exceptions.

All costs of constructing, reconstructing and acquiring rights-of-way for highways in the state highway system shall be borne by the state. However, when a county or incorporated city in which a state highway is located, or is to be located, desires a higher standard of construction or reconstruction than is planned, the county or city may, with the approval of the board, pay the additional cost.