From a March survey of several countries, America stands out as expecially supportive of a diverse society:
I’m not a bit surprised: much of our unmatched greatness lies in our embrace of universal principles and cosmopolitan values, offering as they do a free & equal place for newcomers from the world over. (We are now and have been a great country; we don’t need to be made again what we already are.)
My forefathers came to this continent well before the Revolution, believing & knowing from their arrival onward that those later arriving from other parts of the world would only enrich the American experience, and make this country stronger.
See, Americans more likely to say growing diversity makes their country a better place to live @ Pew Research Center.