Texas border dispute

Situation in the USA is tense; there is currently a severe border management dispute between the central government and the state government of Texas which looks serious enough to be a possible cause for declaration of independence of Texas, followed by at least half of American states. At worst, this would cause a civil war; at best, there might be extraordinary measures such as complete closure of borders and inability to leave America. Things are already not good there, but they might suddenly get incredibly worse.