No. Texas cannot legally secede from the United States.
Texas v. White (1869) — U.S. Supreme Court, 5-3 decision:
"The union between Texas and the other States was as complete, as perpetual, and as indissoluble as the union between the original States. There was no place for reconsideration or revocation, except through revolution or through consent of the States."
Chief Justice Salmon Chase wrote for the majority: The Constitution "looks to an indestructible Union, composed of indestructible States." Secession is unconstitutional.
"Texit" advocates exist (Texas Nationalist Movement, ~200K supporters claimed). Polls: 15-30% *sympathy*, <10% *active support*. No legal pathway. Texas GOP platform included secession referendum plank (2022) — symbolic, not actionable.
Texas's economy ($2.4T GDP, 9th globally), military infrastructure (15 bases), and federal funding ($60B+/yr) make separation fantastically complex even if legal.
Bottom line: Texas v. White stands. No court has overturned it. Secession requires revolution or national consent — neither forthcoming.