For a good conclusion, just sum up what you have said in your paper.
In conclusion the immigration effects everybody, not only the immigrants. If we keep denying immigrants this is going to cause many political problems. They should have the rights everyone else haves.(right here restate your introduction sentence)
End it where you began. America. The great expirement. Settled by pilgrims trying to escape taxation and religious persecution. The heights of our society despite how young the country is. The contributions of the Chinese who worked as railroad excavators or the black experience where the majority of the old wealth came from (the exploitation of slavery) the contributions of everyone that came here either through ellis island or on a different ship (other than the mayflower) or or or. The story itself is huge because so many different nationalities made this country what it is. Or should i say what it was because now the borders are wide open and millions are streaming in, way too many for our fragile economy to continue supporting. I doubt you can give it a good ending unless you fictionalize it. The conclusion is that the expirement worked, we are mutli-cultural nation that rose to great heights because of the contributions of many.