Great short old piece by Matt Yglesias:

[T]he specter of truly open borders is such an obvious specter for
nativists to raise that proponents of more liberal immigration laws had
better have something sensible to say about it.

Indeed, the nativists I’ve privately and publicly encountered routinely claim we’re already in a world of open borders, and insist I’m just a more honest version of Obama or Merkel.  As I explained after arguing with Mark Krikorian, head of the Center for Immigration Studies:

Mark paid me a nice compliment, calling me an “honest man” willing to
unreservedly defend mass immigration.  But he paired this compliment
with harsh words for mainstream pro-immigration thinkers.  Mark seems to
think that they secretly agree with me, but aren’t honest enough to
admit it.

What evidence does Mark have for his conspiratorial
view of his mainstream opponents?  None that I’ve seen.  He’s just
imputing fanciful hidden motives to people he barely knows.  Why
fanciful?  Well, I’ve talked with plenty of mainstream pro-immigration
thinkers.  If anything, my presence inclines them to exaggerate their
support for immigration.  Still, they’re sadly unfamiliar with the case
for open borders, and almost as quick to reject the idea as Mark.

The sad reality is that mainstream pro-immigration thinkers favor moving from our current world of 98% closed borders to maybe 97% closed borders.  But xenophobia is so rampant that even these tepid reforms sound like the end of the world to at least a quarter of American natives.