Ariz. Rev. Stat. § 11-113
Pinal county, the county seat of which is Florence, is bounded as follows:
Commencing at the point where the eastern line of range one east intersects the second standard parallel south, being the southeast corner of Maricopa county; thence east on such parallel to the point where such parallel intersects the eastern line of range eighteen east; thence north on the eastern line of range eighteen east to the point where such line intersects the Gila river; thence down the Gila river to the junction of the Gila river with the San Pedro river; thence in a direct line to a point two hundred fifty yards west of the place where the "Mineral Creek Mill" stood on February 8, 1881; thence in a direct line to a mountain known as the "Water Shed," which lies about a half mile east of Pinal ranch; thence to a point where the northern line of township one north intersects a direct line between the Water Shed mountain and the mouth of Tonto creek; thence west on the north line of township one north and along the southern boundary of Maricopa county to the point where such line intersects the eastern line of range seven east; thence south on the eastern line of range seven east to the point where such line intersects the southern line of township two south; thence west on such line to the point where such line intersects the Gila river; thence down the Gila river to the point where such river intersects the eastern line of range one east; thence south on such line to the point where such line intersects the second standard parallel south, the place of beginning.
A.R.S. § 11-113