N.C. Gen. Stat. § 160A-561
It is hereby found, determined and declared that the creation of the authority and the carrying out of its corporate purposes is in all respects for the benefit of the people of the State of North Carolina, for the improvement of their health, welfare and prosperity, and for the promotion of their traffic, and is a public purpose, and that the authority will be performing an essential governmental function in the exercise of the powers conferred upon it by this Article, and the State of North Carolina covenants with the holders of the bonds that the authority shall be required to pay no taxes or assessments upon any of the property acquired by it or under its jurisdiction, control, possession or supervision or upon its activities in the operation and maintenance of the project or any tolls, revenues or other income received by the authority and that the bonds of the authority and the income therefrom shall at all times be exempt from taxation, except for transfer and estate taxes.
N.C. Gen. Stat. § 160A-561