The problem with Minnesota is the same problem with Germany:
1. a state far from the border being overrun,
2. encourages foreigners to overrun it, against the wishes of the other states,
3. some of the foreigners move to that state, but not most of them,
4. fights with the other states, to keep the foreigners around,
5. demands the other states financially support the migrants,
6. other states get pissed off and stop taking it,
7. gets hit. Cries.
Their behavior puts into question the joint border, but the wealth of the states is largely based upon the freedom of movement between the states. If MN wants an open border, but TX doesn't want that, is there a moral obligation to side with MN?
This is the situation that led to BREXIT, after all. Should TX leave the Union?