Only one poll, yes, but here goes:
61% of Democrats say “improving border security and restricting illegal immigration” would strengthen democracy
To be clear, I don’t consider this good news. The broader point is that I genuinely do not understand Bryan Caplan’s argument that there is no backlash worry from humongous levels of immigration. I see that Angela Merkel let in one million Syrian refugees (which I favored and still favor, by the way), and that strengthened “Far Right” anti-immigrant parties throughout Europe. I see Brexit as in part motivated by a fear of loss of control of immigration. I see that Donald Trump focused on the immigration issue to win the Republican primaries and debates leading up to the 2016 election. The government in Singapore is now facing a major backlash from earlier high levels of in-migration.
How can there not be a backlash from open borders?
The actual, in practice backlash against open borders simply would be to close the borders/limit entry once again, rather than anything too dramatic. But if you continue with a “this lectern is made of ice” counterfactual where the open borders continue against what would otherwise be the political equilibrium, what exactly would be the backlash? I, for one, am afraid to find out. So we want “more open” borders, but not open borders per se.
And no, I am not persuaded by data from pre-1920 America, when borders were largely open and most parts of the world sent basically nobody, and furthermore there was not much of a welfare state. And we did in fact restrict Chinese immigration to California, because of (irrational) backlash.