The boundaries of the county of Rio Arriba are as follows: on the south from the Puertecito of Pojuaque, drawing a direct line toward the west in the direction of the mesilla of San Yldefonso; from the mesilla crossing the Rio del Norte toward the west and continuing until it reaches the boundaries of the territory; drawing a direct line from said Puertecito de Pojuaque toward the east until it reaches the last house of the town of Cundiyo, toward the south, continuing the same line until it reaches the highest point of the mountain of Nambe; from thence, following the summit of the mountain toward the north, until it reaches the southern boundary of the county of Taos; this shall constitute the eastern boundary, and on the north the boundary of the county of Taos, and on the west the boundary line of the territory.

History: Laws 1851-1852, p. 291; C.L. 1865, ch. 42, § 5; C.L. 1884, § 246; C.L. 1897, § 512; Code 1915, § 1099; C.S. 1929, § 33-1901; 1941 Comp., § 15-1901; 1953 Comp., § 15-21-1.

Compiler's notes. — After the creation of Rio Arriba county by the above section, the western part of Taos county was added thereto by Laws 1880, ch. 46, § 2 which read: "Hereafter all that portion of the county of Taos, on the west side of the public road leading from the Hot Springs in the county of Rio Arriba, to Conejos, in the state of Colorado, is hereby annexed to the county of Rio Arriba," thereby making the county of Rio Arriba constitute the northwest portion of the state. Other provisions concerning the boundary with Taos are found in 4-21-2 NMSA 1978.

San Juan county was created out of the western portion of Rio Arriba county in 1887, and other changes have been made in the boundaries.

The present boundaries of Rio Arriba county may be described as follows: commencing on the San Juan river at the point where it crosses the Colorado-New Mexico state line; thence [description from 4-24-1 NMSA 1978] following the San Juan river to its intersection with the range line between ranges 7 and 8 west; thence south on said range line to the seventh standard parallel north; thence west on said standard parallel to the northwest corner of township 28 north of range 7 west; thence south on the range line between ranges 7 and 8 west to the sixth standard parallel north; thence west on said standard parallel to the northwest corner of township 24 north of range 7 west; thence south on the range line between ranges 7 and 8 west to the southwest corner of section 18 township 24 north of range 7 west; thence east [description from 4-23-1 NMSA 1978] on the center of township 23 north to the New Mexico principal meridian; thence south on the principal meridian to the fifth standard parallel north; thence east on said standard parallel to the range line between ranges 6 and 7 east; thence south on the range line between ranges 6 and 7 east to the southwest corner of section 18 in township 20 north of range 7 east; thence east [description of Espanola precinct transferred to Rio Arriba county by 4-26-2 NMSA 1978] along the center of township 20 north to the range line between ranges 8 and 9 east; thence north-northwesterly across Arroyo Seco to the center line of U.S. highway 285; thence westerly along the center line of the highway approximately 1,300 feet to a point which bears south 14 degrees 19 minutes west 32.44 feet from the southeast corner of small holding claim No. 532; thence northeasterly to a point on the center line of the Santa Cruz river; thence west 3,060 feet to the center of highway 285 at the north end of the bridge over Santa Cruz river; thence northerly along the center line of U.S. highway 285 to a point opposite the southwest boundary of small holding claim No. 412; thence northwesterly on the southwestern boundary of said small holding claim to the east bank of the Rio Grande; thence northerly along the east bank of the Rio Grande to the fifth standard parallel north; thence east [description from 4-26-1 NMSA 1978] on the fifth standard parallel north to the range line between ranges 11 and 12 east; thence south on said range line to the point where it crosses the mountain of Nambe; thence easterly and northerly [description from 4-21-1 NMSA 1978] along the summit of the mountains to the point where the line described as being a straight line from the last house of Las Trampas on the south side southeasterly to the junction of the Mora and Sapello rivers [4-29-1 NMSA 1978] intersects the top of the divide.

Cross references. — For change of boundary between Rio Arriba county and Taos county, see 4-21-2 NMSA 1978.

For original borders of San Juan county, see 4-24-1 NMSA 1978.

For attachment to Rio Arriba county of Espanola precinct of Santa Fe county, see 4-26-2 NMSA 1978.

For original boundaries of Taos county, see 4-29-1 NMSA 1978.