Some libertarians, who would normally be all for open immigration, have expressed concern about -- in the name of liberty -- allowing into the country people who will generally vote against it. I have at times shared this concern but in the end find it wanting.
However, I have personally observed this happening in both of the recent states in which I have lived (Arizona and Colorado). But the source of the problem has not been immigration from Mexico or any other country but from California. Californians seem hell-bent to escape the mess they have made of their state. They run to other states complaining of the disaster they are escaping. And then they proceed to vote for the same taxation and regulatory policies that screwed up California.
Arizona state politicians are excited to get all that new income tax money. While I am happy to see new wealth and talent flowing into our state, I fear that these new immigrants are plague carriers, bringing the virus of out-of-control state power to heretofore only mildly infected states.