You're dodging. I didn't ask if it was popular or even feasible (locking down the U.S. like East Berlin isn't feasible either). Just whether or not it's a good idea to restrict immigration from low income states with low unemployment to high income states with higher unemployment. So what do you think, good idea, or not?
There's a thousand answers to this question including the need for population control
Population control? You think the government should regulate how many babies people have? You're starting to sound like a statist, not a Reaganite. Who are the busybody bureaucrats that know how much population the U.S. 'should' have at any given time?
and the welfare state which will never be repealed,
Ah, finally we hit upon the real enemy. Stay focused on socialism, not immigration, because it's the real enemy. The welfare state isn't eternal, it's self defeating.
the one that comes to mind more than anything is national security. There are bad people out there who don't like us and do not need importing.
They can walk from Afghanistan to Pakistan, but a trek through the Canadian woods or the Mexican desert is too tough? If you think the U.S. federal government, or any other entity, can 'secure' the borders you've been duped.
The Constitution of the United States protects American citizens only from government tyranny, not everyone else in the world. Of course people in the country are free to procreate to their hearts content, and as was mentioned in a previous post immigration policy should proceed from there.
In the eyes of most of us, it is not desirable for the government to purposely grow the country to half a billion or more. If anyone is being statist, it is the politicians and bureaucrats who are forcing this policy on us against our will.
If you think the U.S. federal government, or any other entity, can 'secure' the borders you've been duped.
No I'm not being duped, I grew up in a can-do country. We are capable of doing a heck of a lot better job of securing these borders than we are now. A little interior enforcement alone would send a signal to would be illegals around the world their presence is not wanted.