As a libertarian (sympathetic Objectivist ) minded person, immigration can not be classified as illegal because or right is granted by the Creator, not based on ethnicity or nation origin, and does not infringe on the rights of others.
The founding fathers have it right "We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness.--That to secure these rights, Governments are instituted among Men, deriving their just powers from the consent of the governed,"
This would include the right of trade with others and migration in a free market system. If a person wants to come to this country and a business want to hire him it not for others to prohibit trade. Much of the restrictions since the 1920's are based on race, and populist notion that violate the principles of individual liberty. furthermore more to declare something illegal it must violate the principals of Life, Liberty and the pursuit of Happiness of another individual, as such there is no victim who rights are infringed upon therefore I can not see how this can be declared illegal.