The Mexican government has been able to gain a great deal of political power inside the U.S. over the years; see that link. If things continue as they are, eventually we may reach some form of de facto power-sharing arrangement where we don't have full control of parts of our territory or our populace. Corrupt, illegal activity-supporting libertarians, liberals, and conservatives would have you believe that's just a conspiracy theory ("reconquista"), but there are currently border areas and the like that are under shared control between other countries. And, there doesn't have to be an actual...