So Bush has a new proposal to reform the USA's immigration system. The usual suspects shriek; the Democrats say little because they know it will favor them. Basically the idea is to implement a guest worker program; this probably looks great to the President because it would be a reserve army of non-voting unemployed who can be kicked out during recessions, thereby making himself look good. (He's probably wishing for some expendable workers that could be exported right now!) I also expect that the neocons like the idea of a greater America. They can knock over foriegn states, true, but they can't conquer the world because they cannot control entire alien populations. But they expect that with our fine public schools, they can beef up America by importing people and Americanizing them. Bush wants to increase the legal immigration rate. But opponents of the guest worker system are right that it will also increase immigration, illegal and legal. People who are here "temporarily" will just stay and go underground. Also, they'll have children - instant new citizens. Then family unification kicks in. No sweat.
Immigration is a conundrum for libertarians. On the one hand, people should have the right to travel and live whereever they want. "We" should not be excluding anyone. There should be no immigration system at all, nor border controls - abolish the entire business. On the other hand, we do in fact have a state, and it is doing what states always do - redistribution to buy support. And immigrants get goodies too; hence, some immigrants come here only as rent seekers. That's wrong - they're exploiting those of us who produce. Knowing all the transfers that go to immigrants on my dollar, I'm definitely inclined when wearing my technocrat hat towards a system of immigration more like Canada's - that is, only let in people when you can be pretty sure they'll pull their weight.
In anarchy, if it were to happen tomorrow and the wealth levels of the world stayed the same, there would be massive immigration into the USA. Why? Because we have massive amount of capital here, and the only way to access a lot of it is to move here. That's why our wages are high, at least, in the short-term sense. (In the long term, we're rich because we are capitalist - more on that anon.) The incorrect, but common understanding of the Hans-Hermann Hoppe thesis (that a stateless society would or could control immigration) is bullshit. Read what Hoppe himself says. In a stateless society, because all property would be privately owned, in theory "they" could collectively stop immigration by refusing to rent or sell to any immigrant. Similarly, in theory "we" can collectively stop crime by simply refraining from any criminal acts. The point is, as always, there is no "we" in anarchy. "We" assumes that everyone in a whole country might act the same way. That never happens, not even in a state that coerces uniformity. We're humans, and there's money to be made. Employers don't care who the employee is as long as the job gets done. Landlords don't care who the tenant is as long as the rent comes in on time.
So the long run goal is clear: no state, no immigration controls, and probably as a result a very high level of immigration. It would all be "legal immigration" looked at from our current point of view, since the entire notion of "illegal immigration" would be inoperative. However, these immigrants would not be responding to the same set of incentives that current immigrants face. They would be getting much more liberty, including the liberty to keep their culture. But they'd not have the power to take money from the current residents involuntarily.
Meanwhile, back in the real world, we face a problem. The welfare state is not going away. It's much easier to reform immigration - which affects nonvoters - than to take even the most transparently wrong welfare off the books. So, what to do? The vdare types would say that's easy: restrict immigration. But to me that's not so clear. If welfare and immigration are intimately tied together, then perhaps the way to undo welfare is to free immigration. After all, arguably it was the early-century restriction of immigration which made the New Deal politically possible. The vdare mindset would say: it's too late for that. "White" people are already close to a minority: soon they will be, and the socialist transfer state will be unstoppable. This is a reasonable argument.
I mentioned earlier that America is rich, in the short run, because we have capital. That's true, but it's also true that we have capital largely because we had capitalism up until the 30s, and even now have a fairly capitalist economy. The long run problem for America is maintain the institutions that permit laissez faire. And for that, allowing untrammelled immigration might well be a problem. Poor people and culturally alien people in general, and low-intelligence (== uncompetitive) poor foreign people in specific, are dangers in a capitalist (more or less) democracy, because they are likely to vote for rents. Bush's proposal can perhaps be seen in this light as somewhat helpful: although it seems to envision much higher immigration, by regularizing the process it should make it much easier for immigrants to come from places that are not physically close to the US - that is, it should increase the proportion of immigrants from places other than Mexico (most specifically) and Central America (in general). If this has the effect of increasing the flow of culturally capitalist, educated, and/or intelligent immigrants from the rest of the world, it may not prove to be destabilizing to liberty as the current immigration pattern is. However, that remains to be seen. Right now, the immigrants which we want from the POV of capitalist America - educated Chinese, basically - are still voting Democratic. But that may yet change.