Texans are proud of their “Don’t Mess With Texas” bumper sticker, and the Bureau of Land Management is about to find out why.

The agency’s Oklahoma Field Office is sticking with the bureau’s position that the federal government has a right to 90,000 acres along the Red River long held in Texas’ control, saying ownership has been settled for generations.“It’s not the BLM making any such claim as to the status of the land,” bureau spokesman Paul McGuire told Breitbart Texas. “That land was a matter that the courts adjudicated decades ago, going back to the 1920s in fact. The Supreme Court settled the matter as to where the public land in the Red River was. So BLM is really just proceeding on those earlier court decisions.”

The bureau announced Wednesday it was taking control over the land, and Texas Attorney General Greg Abbott has sworn to fight it. Now, Texas General Land Office Commissioner Jerry Patterson has joined the battle, disputing the federal government’s position.

Boundaries of land abutting water are determined by erosion, accretion or evulsion, since rivers constantly change course, Patterson told Breitbart Texas. Since the land is privately owned, by farmers and ranchers who cultivate it and pay taxes on it, and since Texas receives royalties from the mineral rights, it makes sense that no one can manage the property better than its vested owners.

If the federal government wants to wrestle control, it will have to conduct a thorough, lengthy and expensive survey to prove its case, and battle Texas in court, Patterson said. He also wondered about the government’s sudden interest in the Red River area, after more than 100 years of neglect.

 “The BLM’s newly asserted claims to land along the Red River threaten to upset long-settled private property rights and undermine fundamental principles—including the rule of law—that form the foundation of our democracy,” Abbott, the attorney general, wrote on his agency’s website. “Yet, the BLM has failed to disclose either its full intentions or the legal justification for its proposed actions. Decisions of this magnitude must not be made inside a bureaucratic black box.”