[Loyalist]

Nineteenth century nativists erred in believing that America could not assimilate large numbers of Catholics, Jews, Eastern, Central and Southern Europeans who were willing to eventually meld with the broader culture.

Twenty-first century multiculturalists err in believing that America can accept large numbers of people who refuse to assimilate into the broader culture.

There may well be limits regarding a culture's ability to assimilate into another culture, and conversely, assimilate others into its own.

[Dan De Quille]

Nineteenth century nativists erred in believing that America could not assimilate large numbers of Catholics, Jews, Eastern, Central and Southern Europeans who were willing to eventually meld with the broader culture.

An exellent point to bring up. This error is the root cause of the complacency that characterizes the "we are a nation of immigrants" crowd; to them, immigration restrictionists appear to be cousins of The Boy Who Cried Wolf.