Ariz. Rev. Stat. § 36-1422
Two or more cities, towns or counties, acting directly, or pursuant to this article through their public housing authorities, may join or cooperate in the exercise, jointly or otherwise, of any or all of their powers under this article for the purpose of financing, planning, owning, constructing, operating or contracting with respect to a housing project located within the area of operation of one or more of the public housing authorities, cities, towns or counties. For such purpose the governing body of a public housing authority, city, town or county may authorize one or more of the public housing authorities, cities, towns or counties so joining or cooperating with it to act in its behalf with respect to any or all of such powers.
A.R.S. § 36-1422