Lines on Earth 1

Drawings from Emory's expedition Report, 1856.

The Guadalupe-Hidalgo treaty put an end to the Mexican-American war in 184. establishing new geographic limits between both nations: from the Rio Grande (in Mexico: Rio Bravo del Norte), the new line would run until El Paso (today: Ciudad Juarez-El Paso), from there to the Gila river and the Rio Colorado Channel, to end in the --already established by the Spaniards-- division between the Alta and Baja California.

The need for the definition of a physical border based on the terms of the treaty prompted the establishment of two survey teams, Mexican and American. Works started in 1849, just a year after the end of the war. Both teams agreed to work in a parallel process, drawing over the landscape a virtual polygonal line defined by a series of boundary stones or “monuments”, numbered from 1 to 250, so that from each one the following milestone could be easily traced.

The American commission was leaded by John Russell Barlett, explorer and adventure story-teller, although many in the expedition team considered his real purpose was rather writing a best-selling book than solving the boundary definition problem. The task fell in his successor, William Hemsley Emory, an efficient and dedicated military man. The Mexican team was leaded by Jose Salazar Ilarregui, a 25 years old civil servant, committed to the task to the point of facing extra cost and payments with his own money.

The Commissions’ work is excellently narrated in the first chapter of the most interesting book Why Walls Won’t Work, Repairing the US-Mexico Divide, from Michael Dear (only in English, so far), from which many data has been taken for the present text. Dear toured the border route several times, locating and documenting the original monuments and describing the successive changes in the landscape. For the author, both Emory and Salazar Ilarregui (he writes “Ylarregui”, while I am using the Mexican spelling) reach the role of true mythical American heroes

The survey was carried out in three phases, not linearly successive, but determined by their difficulty. Both commissions started their works on July, 6^th, 1849 in the Pacific coast, near a ranch from a certain “aunt Juana” (“Tia Juana” in Spanish), which gave way to “Tijuana”. Luz Maria Oralia relates the agreed procedure between both commissions to fix the starting point: a) They would work independently to determine the geographic coordinates of the ends of the line. b) They would determine the azimuth of this line, at both ends. c) They would locate the most central point of the port of San Diego, and once done this, d) They would measure the marine league mentioned in the Treaty.

Soon a spirit of collaboration arose between the two committees, which often resolved their different measurements by splitting by half the differences, in order to avoid new endless negotiating tables. The Mexican team had a technical instrument of inferior quality (it seems they were scammed in the shipment from Paris), which often increased the time needed for measurements. The teams verified their measurements and erected a series of prefab marble or cast-iron milestones. Seven milestones were installed between the Pacific and the Colorado river. Although this number was considered enough, when the separation between two milestones was too large some stone mounds were erected as intermediate boundary markers .

Second phase was held along the natural border of the Rio Colorado, where the commissions found many difficulties and hardship. In many areas, the river spread and divided in many branches , in a way that it was very difficult to specify the main channel, axis of the border. The, sandy and unstable fluvial lands (with dunes in the mouth of the river), made difficult the placement of landmarks. The third and last part, between El Paso and the Colorado River, was developed in 1855, relatively faster than the previous two, having both teams already greater experience.

Finally, both teams issued their respective reports. In June, 1856, Salazar and Emery met in Washington, where they agreed to make a double set of maps (one for each of their respective governments) in two series at different scales: a general cartography in six plans (scale: 1/600.000) and a detail cartography of 54 plans at scales 1/30.000 (California) and 1/60.000 (all the rest). Original Mexican plans are kept in the Mapoteca Manuel Orozco y Berra, in Mexico city, while the Americans are deposited in the National Archives in Maryland (NARA). According to Dear. They are completely different plans, while Luz Maria Oralia Tamayo, from the Geographic Institute of the UNAM maintains that the common basis of both plans is the same, although with  different drawings and annotations in both different languages.
(text: RG)