On January 11, 2024, the Texas National Guard took control over Shelby Park, a 47-acre (19 ha) area of parkland in the town of Eagle Pass, situated along the Rio Grande river that separates the United States from Mexico, after Texas Governor Greg Abbott signed an emergency declaration to close down the park. In his declaration, Abbott cited the Mexico–United States border crisis and the need to secure the border. The Texas National Guard blocked U.S. Border Patrol agents from patrolling the area, which the Border Patrol had been using to hold migrants in recent weeks.Following the closure, three migrants were found drowned in the Rio Grande. They were subsequently identified by Mexican authorities as a 33-year-old woman and her two children, aged 10 and 8. The U.S. Border Patrol said that they had alerted the Texas National Guard that a group of migrants were in distress in the waters outside the boat ramp in Shelby Park but that the National Guard did not take action to rescue the migrants. Texas lawyers responded that the National Guard was only alerted after the three had drowned, and that the National Guard had not spotted any migrants. Mexican authorities said that the boat never entered U.S. territory.On January 22, the Supreme Court of the United States issued an order to vacate an injunction by the 5th U.S. Circuit Court of Appeals that prevented Border Patrol agents from cutting concertina wire, which the National Guard had been using to make a fence in Shelby Park. The ruling concerned an earlier dispute and did not address Texas deploying razor wire or blocking federal officials from the park. On January 24, Abbott responded by stating that Texas would refuse to let federal authorities access the park, vowing to "protect the sovereignty of our state". A military standoff between state and federal authorities over immigration is unique in modern American history, with constitutional law professor Charles "Rocky" Rhodes and an editorial in the San Antonio Express-News saying it may signal the start of a constitutional crisis.In the aftermath of the Supreme Court's decision, 25 other Republican state governors (all of them with the exception of Vermont governor Phil Scott) announced their support for the Texas government in the dispute, as did U.S. House speaker Mike Johnson. Florida governor Ron DeSantis additionally committed to sending more resources after previously sending the Florida National Guard to reinforce the Texas government. Oklahoma governor Kevin Stitt pledged to deploy the Oklahoma National Guard to support Texas. Other state and national Republican officials backed Texas.On January 23, the Department of Homeland Security issued an ultimatum to Texas attorney general Ken Paxton ordering the removal of "obstructions" along the border and to grant Border Patrol full access to Shelby Park by January 26. On January 24, Democratic Texas representatives Joaquin Castro and Greg Casar called for U.S. president Joe Biden to establish federal control over the Texas National Guard.