one, to the point where it strikes the southern boundary of New Mexico; thence westwardly along the southern boundary of New Mexico (which runs north of the town called Paso) to its western termination; thence northward along the western line of New Mexico until it intersects the first branch of the Rio Gila (or if it should not intersect any branch of that river, then to a point on said line nearest to said branch, and thence in a direct line to the same); thence down the middle of the said branch of said river until it empties into the Rio Colorado; thence across the Rio Colorado, following the division line between Upper and Lower California to the Pacific Ocean.  The southern and western limits of New Mexico mentioned in this article are those laid down in the map entitled ’Map of the United Mexican States, as organized and defined by various acts of Congress of said republic, and constructed according to the best authorities.  Revised edition.  Published in New York, in 1847, by J. Disturnell’; of which map a copy is added to this treaty, bearing the signatures and seals of the undersigned plenipotentiaries.  And in order to preclude all difficulty in tracing upon the ground limit separating Upper from Lower California, it is agreed that the said limit shall consist of a straight line drawn from the middle of the Rio Gila, where it unites with the Colorado, to a point on the coast of the Pacific Ocean distant one marine league due south of the southernmost point of the port of San Diego, according to the plan of said port made in 1782 by Don Juan Pantoja, second sailing master of the Spanish fleet, and published at Madrid in the year 1802, in the atlas to the voyage of said schooners Sutil and Mexicana; of which plan a copy is hereunto added, signed and sealed by the respective plenipotentiaries.

“In order to designate the boundary line with due precision upon authoritative maps, and to establish upon the ground landmarks which shall show the limits of both republics, as described in the present article, the two governments shall each appoint a commissioner and surveyor, who, before the expiration of one year from the date of the exchange of ratifications of this treaty, shall meet at the port of San Diego and proceed to run and mark the said boundary in its whole course to the mouth of the Rio Bravo del Norte.  They shall keep journals and make out plans of their operations; and the result agreed upon by them shall be deemed a part of this treaty, and shall have the same force and effect as if inserted therein.  The two governments will amicably agree regarding what may be necessary to these persons, and also as to their respective escorts, should such be necessary.

“The boundary line established by this article shall be religiously respected by each of the two republics, and no change shall ever be made therein, except by the express and free consent of both nations lawfully given by the General Government of each in conformity with its own constitution.

  “ART. 6 gives citizens of the United States free navigation
  of the Gulf of California and the Rio Colorado below its confluence
  with the Gila.