a major, ongoing concern in the u.s. is that of illegal immigration. as is so often the case, the mainstream debate revolves around logic (or the lack thereof) stemming from false, assumed premises. most participants assume the legitimacy of the state, lack an understanding of private property, have a very poor, if not non-existent understanding of economics and are influenced, surprisingly transparently, by ethnic and racial biases.
first, let's address the rights-driven, morality of immigration. every person has rights. those rights stem from his entitlement to his own property, the most basic unit of which is his body. all people have the absolute right to do with their property whatever they wish, as long as they avoid infringing the property of others. as the old cliche goes, "your right to swing your fist ends at my nose".
that being the case, people have the right to travel wherever they please as long as they respect the legitimate property of others. no one has the right to stop them from immigrating from place to place except those who may own land being trespassed upon. any attempt to stop immigration outside of one's own land is a violation of the rights of that individual - a crime.
practically, immigration is a boon to an economy. generally, people immigrate for the same reasons they do virtually anything else; as a means to the end of improving the quality of their lives. this is a natural function of markets. as a place becomes more productive and, therefore, wealthier, it attracts those who wish to increase their wealth. it works out, because such economies need new labor to expand production in line with growing demand. it is part of the natural harmonies of human society - the spontaneous order. as more people enter an economy, more goods and services are needed to sustain them, creating higher demand, a continued increase in production expansion, an increase in the need for new labor, etc.
the problems with immigration are a creation, almost entirely, of the state. countries are an abstraction. when one refers to "this country" or "our country", they engage in the fallacy of conflating two separate and distinct groups. there is no "country", only (1) people engaging in activities every day, attempting to better their lot in life according to their own values and (2) those, like governments, attempting to live at the expense of others through force. they are separate, competing groups. the latter group has established a boundary with another such neighboring group (like the boundary between the u.s. and canada or mexico) inside which, each will exploit its resident population. these turf boundaries are sanitized with the term "borders".
governments will, in order to control populations, set up laws governing immigration. they don't want anyone to be able to conduct business inside their boundaries without being able to exploit them. so, they set up checkpoints at borders and keep a strict watch on who enters and who leaves. they violate the rights of people to move freely in order to better conduct their criminal scheme. they demonize "illegal" immigrants who use welfare, but do not pay into the system, creating friction between immigrants and legal citizens who must fund welfare. it's clever, because it hides the fact that the whole scenario is a product of the state creating and forcibly funding a welfare program in the first place. governments might point out how much drug-related crime immigrants are engaged in, but this, too, is a result of the state's outlawing of drugs.
illegal immigration is a problem created and exacerbated by government. the individuals referring to themselves as "the government" have, just as any other people, no right to restrict the movement of others. in violating the rights of immigrants, they cause the weakening of an economy. there is nothing wrong with immigration, legal or illegal. eliminate the state and you eliminate the problem.