As refugees from war... The U.S. does that for refugees in many other wars as well.
As for the rest of your screed, I find it very disturbing. My ancestors were "riffraff" who came over from Europe during the late 19th century. As were yours, I'm sure. And I think that those immigrants made America a much better place. Therefore, I have a similar view of current immigrants. If someone is willing to work hard and better himself or herself, then I think that he or she should be welcomed into the U.S. The more legal immigration there is, the better..
I never said all immigrants were/are riffraff. Many in recent years, however, are out for welfare, commit crimes, refuse to learn the language, have an enormous sense of entitlement, etc.
There are many good people among immigrants, and millions of good people would want to migrate to this country. The problems is numbers. This country already has too many people.
If this keeps up we'll end up a 3rd World country.