North Carolina General Statutes Chapter 95. Department of Labor and Labor Regulations § 95-102. Certain payments to and agreements to pay labor organizations unlawful

It shall be unlawful for any carrier or shipper of property or any association of such carriers or shippers to agree to pay, or to pay, to or for the benefit of a labor organization, directly or indirectly, any charge by reason of the placing upon, delivery to, or movement by rail, or by a railroad car, of a motor vehicle, trailer, or container which is also capable of being moved or propelled upon the highways and any such agreement shall be void and unenforceable.