Remeasuring the border

Between 1891 and 1896, because the cairns that had been erected by William H. Emory during the measurement of the border in 1855, had been severely damaged, Engineers J. W. Barlow and Jacobo Blanco, from the International Boundary Commission, undertook another remeasurement, and installed the metal obeliscs that still remain.

The most important finding of this commission was that Emory had made several mistakes along his measuring trip, and Mexico lost 847.47 square kilometers of land (209,414 acres).

The error is originated in two sections:

• along paralel 31° 20´,
• And along the azimutal line.

The first part of the error, along paralel 31°20´ covers a surface of 77.41 square kilometers (19,128 qcres) of loss for Mexico. For instance, in Nogales the real border according to the Treaty (that is paralel 31° 20´) is actually located some 180 feet further North from where the border was established.

However, the main error in the boundary is located along the Azimutal line. According to the Treaty, the border should start from the point located in the intersection of paralel 31° 20´with meridian 111°. This point is located in the ground some 2.09 miles West of the Mariposa crossing. However, Emory established this geographic point at 7.2542 kilometers (4.507 miles) further west. The end result is that only along this pastel piece formed part of the error, Mexico lost 770.06 square kilometers (190,285 acres).

If we add the errors along both sections of the border, they reach a total of 209,413 acres.

The Diaz government would unsuccessfully try the return of this surface that Mexico lost. We can see at the right a copy of the first page of the first reclamation that the Mexican Ambassador in Washington, Matias Romero, would make to Secretary Sherman on August 9, 1897.

The arguments made by the US, on answering to the Mexican petition, were that this region had already been populated, and the cost of relocating them would be too high, while at the same time it wouldn´t be worth the trouble, as the surface was too small.

Mexico then answered that in reality the surface was small, if we consider the whole of the surface lost by Mexico, while at the same time the option remained of changing the returned surface, to a rectangle located along the "step" in the border, located between paralels 31°20´and 31°47´(that is, East of today´s Agua Prieta), which would avoid the problems associated with relocating the population, as this region wasn´t populated. The United States answered that they would "study" the proposal. However, they didn´t answer again.

Then the Mexican Revolution would follow with the result that this mistake hasn´t been corrected yet.