Context: The United States government has a federal structure, unlike most governments. This means that the federal/national government and the state governments have distinct divisions in power and responsibility. For example, the highest level of law enforcement that can legally exist is at the state level. Rogue Supreme Courts have made illegitimate and tyrannical rulings to grant the federal government some police power, even though the Constitution and Bill of Rights clearly reserve police power to the states.
That only the states have police power was implicitly understood prior to the ratification of the Tenth Amendment, the final amendment in the Bill of Rights. The Tenth Amendment states that whatever powers and rights are not expressly granted to the federal government in the Constitution shall be reserved to the states or to the people. Since police powers are not expressly granted to the federal government, only the states may enforce laws. Again, illegitimate rulings by rogue Supreme Courts have granted this power to the federal government with no legal basis.
Dual federalism is this divide between the power of the federal government and the state governments. Over time, especially since the administration of President Franklin Delano Roosevelt, dual federalism has been eroded without meaningful constitutional amendments. Most people are generally satisfied with this, but when a state has significant differences with the federal government on the enforcement of the law or on matters of authority, the easy solution without having a civil war is to return to the state that which rightfully belongs to it: The powers implicitly reserved to it by the Constitution.
Other than those illegitimate Supreme Court rulings, only Texas has the authority to enforce border laws in Texas. The federal government, technically speaking, has no authority to enforce border laws anywhere, unless a constitutional amendment is ratified granting it such power.