40-1112. Qualifying bodies which may form authority; purposes A. A metropolitan public transit authority may be formed by any of the following: 1. The governing body of a municipality, the population of which is not less than fifty-one per cent of the proposed area of the authority. 2. The governing bodies of more than one municipality acting jointly in a county, the combined population of which are not less than fifty-one per cent of the proposed area of the authority. 3. The board of supervisors of a county if the population of the unincorporated areas of such county within the proposed authority area and the population of any one or more contracting municipalities when combined is not less than fifty-one per cent of the population of the county. B. Such an authority may acquire, own and operate a metropolitan public transit system including all appurtenances thereof in the area of the authority.
Arizona Legal Code