...Despite a reasonable history of being a melting pot (tossed salad still in some areas) with tolerance to new comers we still go through spells where a vocal group can still unilaterally hate whole classes of people based upon religions, skin color, country, or political preferences.
My opinion is that there is a significant difference in the immigrants of today vs those when the nation was younger. In those days, it seems that the newcomers were more interested in integrating/assimilating themselves into the American society and culture. Learning and speaking the language for an example. Today they seem like they want to be the same, but separate. We are just a society of hyphenated Americans not just plain ol' Americans. There is less and less United States of America ... wait maybe that' not such a bad idea...signed Texan-American.
