Has any U.S. state or territory ever left peacefully and legally?

We will answer this one straight, because an honest answer is more persuasive than a dodge. No U.S. state has peacefully and lawfully left the union itself, for the simple reason that no state has tried it the modern way: through a clear democratic referendum and a negotiated separation. The question has never been put to the test by the method that actually works. That is not the same as saying it cannot be done.

The one time borders were redrawn peacefully, the union allowed it

There is a domestic precedent for a peaceful, lawful change of this kind, and it cuts in our favor. In 1863, West Virginia separated from Virginia and became its own state. It did so through constitutional procedures, with the consent of a Virginia legislature and the approval of Congress, exactly as Article IV of the Constitution requires for forming a new state. West Virginia did not leave the union; it left one state to become another within the union. But the lesson stands: when the consent procedures are followed, a peaceful, lawful redrawing of American political boundaries is not only possible, it has already happened. The machinery of consent exists.

The only state to attempt to leave the union did it the wrong way

The Confederacy is the example everyone reaches for, and it is the wrong template in every respect. That attempt was tied to slavery, it was carried out by conventions rather than a vote of the whole people, and it was pursued through war rather than negotiation. It tells us nothing about whether a peaceful, democratic, negotiated departure is lawful, because it was none of those things. Pointing at 1865 to answer a 2026 question is a category error. The Confederacy is not the precedent. It is the cautionary tale of how not to do it.

The peaceful, lawful model is happening all over the modern world

Step outside the United States and the picture is completely different. The democratic world has built a working, lawful model for exactly this, and it has used it repeatedly. Britain left the European Union by referendum, and TEXIT is named for it. Scotland was granted a lawful independence referendum in 2014 under an agreement with the United Kingdom. Quebec voted on independence in 1995 within a clear legal framework, and Canada's Supreme Court later confirmed that a clear vote would compel negotiation. The Czech Republic and Slovakia divided peacefully in 1993 and were recognized within weeks. These are constitutional transitions: lawful, negotiated, and accepted by the international community.

"No state has done it" is an argument for being first, not for staying put

Notice what the objection actually proves. It does not show that leaving is unlawful. It shows that no state has yet pursued the lawful, modern method. Every nation that ever restored its independence was, at some point, the first to do it under its particular circumstances. The absence of a prior American example by referendum is a statement about history, not about law. The law permits the path. The international precedents show the path works. What remains is for Texans to walk it.

The bottom line

No state has left the union peacefully and lawfully, because none has tried the proven modern route of a clear referendum and a negotiated separation. But the consent machinery for redrawing American boundaries exists and was used for West Virginia, the Confederacy is the example of how not to proceed, and the democratic world has a working model that has succeeded again and again. Texas would not be repeating a failure. Texas would be the first U.S. state to do it right.