New Mexico’s International Border

New Mexico’s 179.47 miles of international boundary are the result of the Gadsden Treaty of 1853. The line was originally surveyed in 1855 by Major William H. Emory, commissioner, chief astronomer and surveyor of the International Boundary Commission. On the entire 697.67 miles long land boundary between the United States and Mexico (including about twenty-four miles along the Colorado River) Major Emory set a total of only fifty-two monuments.

After leaving the initial monument (#1) on the Rio Grande the next two monuments on the latitudinal arc of 31 degrees and 47 minutes were ½ mile and three miles distant. Between monuments #3 and #4 was a gap of forty-seven miles. It was thirteen miles further to #5, another eight miles to #6, thirteen more to #7, and finally fifteen miles to the end of the nominally 100 miles long parallel (it is actually only 99 miles long) at monument #8. Monument #9 marked the approximate midpoint and #10 the south end of the thirty-one miles long meridian that forms the boot-heel, the bottom of which is in latitude 31 degrees and 20 minutes. Continuing west, monument #11 was never found by subsequent surveyors, and it takes more than twenty-eight miles to get to monument #12.

The boundary was so poorly marked that only eight month after it’s establishment U. S. Deputy Surveyor John W. Garretson had to rerun eighteen miles of it in order to set a closing corner for the New Mexico Principal Meridian. Nevertheless, on June 2, 1856 President Pierce proclaimed the boundary surveyed.

For almost thirty years this vague border left local residents wonder whether they were living in the United States or in Mexico. Ranchers quarreled over water holes, miners fought over minerals, state and federal officials of the two countries argued over jurisdiction. At a convenient pile of rocks of unknown origin near Antelope Wells in Hidalgo County, Mexico collected custom duties three miles inside American territory. As complaints grew louder, the two governments appointed delegates who met in Washington in July 1882, where they decided to send military officers to inspect the entire line and submit a report.

The American inspection team of the revitalized Boundary Commission was led by Lieutenant Thomas W. Symons, a thirty-four-year-old West Point graduate. Symons was a competent and experienced surveyor who set out in July 1883 to inspect the Emory line. Only a few of the original monuments had survived in good condition. Originally build twelve feet high they had been conspicuous enough, but were too far apart to adequately mark the boundary. Symons recommended a resurvey of the entire line and enough additional monuments so as to make them easily intervisible.

It took another ten years for Congress to take action. In 1892 a newly appointed commissioner, Lieutenant Colonel John W. Barlow, and his Mexican counterpart Jacobo Blanco resurveyed the entire boundary between El Paso and the Pacific Ocean. Emory’s monuments were repaired and new cast-iron monuments were installed, twelve inches square at the base and six feet high, on concrete foundations, set roughly at intervals of 2.5 miles. With monument #1 at the Rio Grande and #258 at the Pacific, New Mexico’s major angle points are monuments #1, #40, #53, and #71 (at the Arizona line). Since 1975 all 258 monuments are designated angle points and additional monuments, where necessary, are considered to be only line markers.

Yes, as you might have guessed, the resurvey showed that the boundary is not were it was supposed to be. But the treaty makers knew the limits of the art and science of surveying and had forestalled future disputes by inserting the appropriate language into the treaty. In Article I it says: “… that line shall be alone established upon which the commissioners shall fix, their consent in this particular being considered decisive and an integral part of this treaty, without necessity of ulterior ratification or approval, …”

Which makes any discussion as to accuracy moot.