Any county in the State of Nebraska may issue revenue bonds to construct or to aid in the construction, or complete the construction of any highway, wagon, vehicle, or automobile bridge within the State of Nebraska and any adjoining state across any river, navigable or nonnavigable stream, forming a boundary line between any county within the State of Nebraska and any other state of the United States, which revenue bonds shall be payable solely from the revenue and funds from such bridge and as to which, as shall be recited therein, the county shall incur no indebtedness of any kind or nature, and to support which the county shall not pledge its credit nor its taxing power nor any part thereof. As a part of the cost of any such bridge, the county may include (1) the costs of any river structures approved by the special engineer for the project and with the approval of any required state or federal agency having jurisdiction thereof, and (2) the costs of, or assist in the payment of the costs of, any approach structures or roads not over ten miles from the actual bridge structure. Any such county may levy, collect, and distribute tolls and use the same in payment of the principal and interest on such revenue bonds and for the maintenance, repair, and operation of any such bridge. It may accept gifts and grants of money from the United States Government or any corporation or agency created, designed, or established by the United States, and may enter into contracts with the United States or such corporations or agencies, and do everything necessary thereto, and to construct or aid in the construction or to complete the construction of any such bridge or bridges.