Ariz. Rev. Stat. § 11-103
Apache county, the county seat of which is St. Johns, is bounded as follows:
Commencing at a point where the boundary line between Arizona and New Mexico intersects the thirty-seventh parallel of north latitude, being the northeast corner of this state, and being more particularly described as the four corners monument, thence south along the boundary line between Arizona and New Mexico to a point where the first standard parallel north intersects such boundary line, being the northeast corner of Greenlee county; thence due west to the Black river; thence westerly and down the Black river along the northern boundary of Greenlee and Graham counties to the east line of range twenty-three east of the Gila and Salt River Guide meridian; thence north along such range line to the former southern boundary line of the Navajo Indian reservation as established by presidential executive order dated January 6, 1880; thence west along such boundary line to the one hundred tenth meridian of west longitude; thence north along such meridian to the boundary line between Utah and Arizona, being approximately the thirty-seventh parallel of north latitude; thence east along such boundary line to its intersection with the boundary line between Arizona and New Mexico, the point of beginning, being the four corners monument.
A.R.S. § 11-103