Colo. Rev. Stat. § 30-5-157
The boundaries of the county of Pueblo shall be as follows:
Commencing at a point on the western boundary line of said county, as heretofore constituted, where the fourth correction line south crosses the western boundary of said county, thence running due west six miles; thence due south to the summit of the Greenhorn range of mountains; thence southward along said range of mountains to the summit of the Cuerno Verde peak; thence northeast in a straight line to Corral de Toros on the Huerfano river; thence eastward to the Iron Springs; thence due east to the east line of the state; thence north along said east line of the state to a point due east of the northeast corner of said county, as heretofore constituted; thence west to the northwest corner of said county, as heretofore constituted; and thence south to the place of beginning.
C.R.S. § 30-5-157