In brief
Mexico’s Foreign Ministry stated that only the federal governments of Mexico and the United States can determine the international boundary, citing the 1970 Boundary Treaty and the authority of the International Boundary and Water Commission. The statement came after Texas’ General Land Office declared nine islands on the Rio Grande as Texas property, which Mexico rejected and pledged to monitor.
In a statement released on Tuesday, the Mexican Foreign Ministry asserted that the border between Mexico and the United States cannot be altered by a U.S. state government, a response to the Texas General Land Office’s claim over nine islands in the Rio Grande.
The claim, announced in early October, came from Texas’s state agency led by Commissioner Dawn Buckingham, who declared the islands to be property of the state of Texas despite their location in the international river that forms part of the Mexico‑U.S. border.
Mexico’s Foreign Ministry reiterated that sovereignty along the Rio Grande is governed by the 1970 Mexico‑United States Boundary Treaty, which states that the boundary in the river follows the center line of the normal channel. The treaty establishes that the land on either side of that line belongs to the country whose side it lies on, regardless of prior ownership.
The ministry emphasized that the International Boundary and Water Commission (IBWC), a joint body authorized by both governments, is the sole authority to determine the precise location of the boundary and, consequently, which side of the river each island falls on. It stated that no U.S. state‑level organization has the power to make such determinations.
Under the terms of the treaty, both Mexico and the United States are prohibited from constructing works that could alter or obstruct the normal flow of the Rio Grande, a point that the Foreign Ministry underscored in its response to the Texas declaration.
The Mexican Foreign Ministry also announced that Mexico will closely monitor any actions taken in the disputed area. It reiterated its commitment to abide by the treaty and to pursue dialogue through the established mechanisms of the IBWC, avoiding unilateral actions that could compromise the treaty’s integrity.
While Mexico did not provide a direct quotation from the ministry officials, the statement was issued through the ministry’s official channels and was reported by Xinhua News Agency on October 31.
The Texas General Land Office’s claim was first made public in an announcement by the agency, which cited state law as the basis for asserting ownership over the islands. However, the ministry’s response made clear that state law does not supersede international treaty obligations or the authority of the IBWC in matters of border demarcation.
Both sides have indicated a willingness to address the dispute through existing bureaucratic and diplomatic channels. Mexico’s pledge to monitor and uphold the treaty suggests that it is prepared to engage with the IBWC should the situation evolve or if any infrastructure changes threaten the river’s normal flow.
As the Rio Grande continues to be a pivotal factor in cross‑border relations, the dispute over the nine islands underscores the ongoing importance of treaty‑based governance and the limited role that state governments can play in redefining international boundaries.
With the international community keeping a close eye on the situation, Mexico’s clear statement reinforces the primacy of treaties in resolving border disputes and signals a reluctance to engage in unilateral actions that could destabilize the longstanding Mexico‑U.S. border arrangement.
