Texas Claims Nine Rio Grande Islands to Keep Out Cartels. Mexico Says Only a Treaty Can

Texas has planted its flag on nine islands in the middle of the Rio Grande, and Mexico's government says the state has no right to do it.

Texas Land Commissioner Dawn Buckingham announced this week that her General Land Office had confirmed nine river islands, about 66 acres spread from the Laredo area down toward McAllen, belong to the State of Texas. That gives the Texas Department of Public Safety and the Texas Military Department clear legal footing to go onto them. "Texas land will never become a safe haven for cartels, human traffickers, smugglers, or other criminal organizations," Buckingham said.

It started with a Border Patrol question

In letters dated Oct. 26 to Maj. Gen. Thomas Suelzer, the Texas adjutant general, and to DPS, Buckingham wrote that U.S. Customs and Border Protection had asked the land office about 28 islands in the Rio Grande "that were previously considered unclaimed or whose ownership had not been established." After reviewing "historical records, surveys, and other relevant information," the office decided nine of them are owned by Texas. Copies went to Gov. Greg Abbott's office and to CBP.

The letter tells the Texas Military Department it "may access these state-owned islands for the purpose of maintaining operational security of our southern border," and adds that all operations must follow state and federal law.

Buckingham was candid that nobody has caught smugglers on these nine yet. "While we have not confirmed criminal activity on these additional islands, past experience has shown how border islands can be exploited by cartels and smugglers," she wrote.

Texas has done this before

The past experience she means is Fronton Island, a 170-acre island in Starr County that Buckingham declared state land in 2023. After that, DPS and the Texas Military Department cleared its brush in what the state called Operation Flat Top. The land office says crime at that border hot spot then dropped sharply.

In her video announcing the new islands, Buckingham said the office had already taken back five islands "that cartels and human traffickers had exploited for criminal activity" during the border crisis. "Today, we have identified nine additional islands that should legally belong to Texas," she said.

Mexico: 'No state authority has that power'

Mexico's Foreign Ministry answered on Friday with a short information note, No. 015/2026. Its first line, translated from Spanish: "The border between Mexico and the United States cannot be modified by the decision of a state government."

The ministry pointed to the 1970 Boundary Treaty, under which the border in the Rio Grande runs down the center of the river's normal channel. It said the International Boundary and Water Commission, which both national governments run, is the body that decides which side of that line each island sits on. "No state authority has that power," the note says. Mexico will "closely follow any action in the zone," it added, and it reminded Texas that the treaty bars either country from building works that could block or divert the river's flow.

Both sides cite the same line

Texas says it used that very test. The land office said Thursday the nine islands "met standards for Texas ownership based on their orientation to the river's center line." Its map draws the international boundary line through the river beside each island, with every one of them on the Texas side.

So the fight is less about where the line is than about who gets to say so. Mexico wants the two-nation boundary commission to rule island by island. Texas says the islands were already on its side of the line, and that it only cleared up who owns them so the state's own troopers and soldiers know where they can go.

The commission has not said anything in public about the nine islands. For now, the state's letters stand, and Buckingham says the land office will share each island's coordinates with state and federal law enforcement.