Immigration is one of those few issues that libertarians can reasonably disagree. It is kind of like the issue of abortion in that regard. There are some good libertarian arguments to be made for both sides of the debate. In fact, with immigration, there is even middle ground that might be reasonable for a libertarian.
I have never really understood those who are really anti-immigration. It is really the heart of America. I'm not sure if these people are racists or just scared of people who might look a little different or speak differently.
Some of the reasons for people being anti-immigration, that may sound somewhat reasonable, are actually reflections of big government that is already in place. There are two primary examples here.
First, some say we can't have open immigration because of the threat of terrorists. Some might even argue against most or all immigration, particularly from specific countries. Many of the terrorists on 9/11 were actually in the U.S. legally, so the current policy didn't stop them anyway. But even if closing the borders were effective (which it wouldn't be), the only reason there are so many people wanting to cause terror in the U.S. is because of the U.S. government. If there were no bombings of other countries, and no blockades, and no coups, and no military bases, and no propping up of dictators, then there would be few people who would ever even care about America. They would certainly have little incentive to hurt Americans.
Second, some say we can't have open borders or any immigration at all because they will collect welfare. Again, this is a symptom of big government. If we didn't have a welfare state, then we wouldn't have to worry about immigrants coming to America to collect free goodies. The only people that would move to the U.S. would be those looking for work (or perhaps vacation).
I have never understood the welfare argument. Welfare does far more harm than good in the long run for most people. Yet, if it actually worked, I would probably feel more sorry for the poor Mexican immigrant who had little opportunity who is just looking for work. Why would I think that some bum in America is more entitled to welfare, just because he happened to be born in a certain area? I'm not saying that all welfare recipients are bums, but my point should be well taken.
It is hard to believe what has happened to America. The land of the free is now the land of taxes, wars, and passports. It used to be that almost anyone could go to America in search of a better life. You had the responsibility of taking care of yourself and your family, but you were free to search for opportunity. It came to a point where immigrants would go through New York Harbor, but even then, they were just checked to make sure they weren't carrying any strange disease. Aside from that, most could enter almost immediately.
I hope we can one day see an America where Americans are not worried about immigrants because of terrorism or welfare, because there will be little of it. Maybe we wouldn't have to worry about drugs either if they are actually legalized. If America becomes free again, then immigration will become a moot point for most people. And if other countries follow suit, then maybe there won't be so many people trying to flee their homeland.
If America stays on its current path, then I don't think Americans will have to worry about immigration anyway. Who will want to come here?