Any municipality, county, parish, highway commission, or other political authority in an adjoining state which has been properly authorized by the laws of that state and the United States may exercise in the State of Mississippi any and all the powers granted in this article to municipalities and other public bodies in Mississippi, subject to the conditions and requirements of this article. In event that the powers granted under this article are exercised solely by a municipality or county, then same shall be exercised by the governing authority of such municipality or county; and in the event that same are exercised jointly, then same shall be exercised jointly by the governing authorities of such political subdivisions.