Ariz. Rev. Stat. § 11-112
Pima county, the county seat of which is Tucson, is bounded as follows:
Commencing at the point where the meridian line one hundred thirteen degrees twenty minutes west longitude, as defined by the Atwood survey of 1918, intersects the second standard parallel south, being the southwest corner of Maricopa county; thence east on such parallel and along the southern boundaries of Maricopa and Pinal counties to the point where such parallel intersects the eastern line of range eighteen east, being the southeast corner of Pinal county; thence south on such range line and along the western boundaries of Graham and Cochise counties to a point six miles north of the point at which the fourth standard parallel south intersects such boundary line; thence due west forty-two miles to the intersection of the line between ranges eleven and twelve east, such point being near the Bustamante ranch as it existed in the year 1899 on Sopori creek; thence due south fourteen miles; thence due west twelve miles to a point; thence due south to the southern boundary line of Arizona; thence westerly and northerly on such boundary line to the point where such boundary line intersects the meridian line one hundred thirteen degrees twenty minutes west longitude, as defined by the Atwood survey of 1918, being the southeast corner of Yuma county; thence north along such meridian line to the point where such meridian line intersects the second standard parallel south, the place of beginning.
A.R.S. § 11-112