So you think Europeans, ie English or French, would be better for the USA than Mexicans slipping into the country?
Methinks you would be wrong. For starters it's often said that the further distance an immigrant comes the better that immigrant will be.
I suggest that Asian immigrants are of more value than Hispanic ones, going by educational standards, standard of living, business accumen etc..
How can, say, a Central American person have more 'right' to be on native American soil than a European or Chinese?