In brief
Mexico’s foreign ministry denied that the U.S. state of Texas could alter the internationally agreed Mexico‑U.S. boundary by claiming possession of nine Rio Grande islands. Citing the 1970 Boundary Treaty and the role of the International Boundary and Water Commission, Mexico stressed that only the treaty and the Commission can determine sovereignty and that neither side may construct works that would affect river flow. Mexico will monitor actions in the area and pursue dialogue through established mechanisms.
Mexico’s Foreign Ministry said Friday that the U.S.-Mexico border cannot be altered by a state‑level government, reaffirming that the demarcation between the two countries must follow standards established by international treaties.
The comment came in response to a declaration by the Texas General Land Office, a U.S. state agency led by Commissioner Dawn Buckingham, which claimed nine islands in the Rio Grande—known in Mexico as the Rio Bravo—as property of the state of Texas.
In its statement, the ministry explained that under the 1970 Mexico‑U.S. Boundary Treaty, the international boundary in the river follows the center line of the normal channel and that line determines sovereignty over the land on either side, regardless of who previously held sovereignty over it.
It further noted that the International Boundary and Water Commission is the body authorized by the two governments to carry out the treaty and has the power to determine on which side of the boundary each island lies, the ministry said, noting that no state‑level government body has the authority to make such determinations.
Under the treaty, neither side may build works that the International Boundary and Water Commission finds could alter or obstruct the normal flow of the river. The ministry stressed that this provision protects the hydrological integrity of the Rio Grande and ensures that neither country can unilaterally change the river’s course for its own advantage.
Mexico pledged to closely monitor any actions in the area and reiterated that it would abide by the treaty governing the two countries’ shared border. It also said it would continue to pursue dialogue through established mechanisms such as the Executive Commission of the International Boundary and Water Commission, which is charged with resolving disputes and ensuring compliance.
The dispute over the islands reflects a broader tension that can arise whenever a natural boundary follows a shifting river channel. While the treaty provides a clear legal framework, the legal question of sovereignty over islands that move with the river remains controversial, and each side has framed the issue in alignment with its own administrative priorities.
By emphasizing the primacy of an international treaty and the role of a joint commission, Mexico highlighted a precedent that bilateral state claims cannot unilaterally alter the boundary agreed upon by the sovereign governments. The stance underscores Mexico’s commitment to international law and the maintenance of a shared, mutually respected border.
