Immigrants flooded into America in the early days to become AMERICANS. After large scale waves of immigrants during the period around WW1, there were racially-motivated immigration quotas passed. Then, the laws changed in 1965 and allowed those in with ideals that are anti-American (not good for America) including those planning to instill Sharia law for instance.
After WW1 until 1965 we would discriminate as to whether or not there was a good reason for someone to enter the US. Folks would be turned away if they were persons without skills, with known diseases, with no family, low-skilled workers from the Third World, etc. (the non-terrorists). Even today, legal permission from many countries to enter the United States is almost impossible to obtain. For example, millions of Haitians wanted to move here after the earthquake and were denied.
Presently, there are hoards wanting to come into the US claiming “refugee status” to get in quickly. But, these are mostly young, Muslim males or families with specific instructions in the Koran to peacefully migrate to other lands to repopulate in order to take over the culture with Sharia law – not good for America. (this is a specific mandate of “Political Islam” which drapes itself in religion.”) From Allen West: “President Theodore Roosevelt believed no man should be discriminated against because of where he was born, but insisted any immigrant who arrives on our shores should become an American in terms of faith, allegiance and language, “If he tries to keep segregated with men of his own origin and separated from the rest of America, then he isn’t doing his part as an American. We have room for but one soul loyalty.”