Claudia Sheinbaum: border commission, not Texas, decides Rio Grande islands

Mexico's President Claudia Sheinbaum said on Tuesday, 3 November 2026, that the state of Texas has no power to decide who owns nine small islands in the Rio Grande, the river Mexicans call the Rio Bravo. Speaking at her morning press conference in Mexico City, she said the question belongs to the International Boundary and Water Commission, the joint body the two federal governments set up to apply their border treaties, and that Mexico would pursue the matter through diplomatic channels. She also linked the timing of the Texas claim to the United States midterm elections held the same day.

Rivers make awkward borders because they move. Sand and silt build up, channels shift and new land appears in the middle of the stream. The 1970 treaty between the United States and Mexico was written to handle exactly this. It fixes the boundary along the centre of the normal channel and gives the binational commission, known in Spanish by the initials CILA, the job of deciding on which side of that line each piece of new land falls. In Mexico's reading, a single US state cannot do that job for itself.

Texas frames the move as a security measure. Buckingham said uncertainty over who owned the islands had limited the ability to monitor and protect them. Texas has made a similar claim before: in 2023 it said Fronton Island belonged to the state, and that claim was disputed by the federal government in Washington, which treated the island as federal property. The new designation goes wider, covering nine islands at once along a busy stretch of the border.

Sheinbaum avoided turning the issue into a quarrel with the US federal government. She placed it with the existing treaty body and with diplomacy, while saying that electoral interest in Texas explained the timing. The search results reviewed for this story did not include a response from the US federal government to Mexico's note, so Washington's position on the new Texas claim is not yet public.

Peepals calculation: The nine islands cover about 66 acres, which is roughly 26.7 hectares (66 × 0.4047) and matches the "about 27 hectares" reported in Mexico; that is an average of about 7.3 acres, or 3 hectares, per island (66 ÷ 9). The nine claimed islands are 45% of the 20 that Texas reviewed (9 ÷ 20). Our calculation from the reported figures.

Short-term: The claim adds a new irritant to US-Mexico relations at a time when the two governments already talk regularly about security, migration and trade. Mexico has put its objection on record through a formal note, and the president has now repeated it publicly.

Long-term: If the dispute reaches the boundary commission, its finding on each island would carry the weight of the 1970 treaty. A state-level claim that is not backed by Washington is unlikely, on its own, to change the international line, but it can shape who patrols the islands on the ground.

Who is affected: Border communities between Laredo and McAllen on both banks; law enforcement agencies on both sides of the river; and the two federal governments, which share responsibility for the treaty.

For readers in India, the case is a clear example of a wider problem that any country with a river border faces: land made and unmade by the water does not fit neatly into lines drawn on a map, which is why treaty bodies and joint commissions exist.

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