Jamelle Bouie has a great post up this morning about assimilation and immigration, riffing off of Ross Douthat's column. Douthat's claim is that the America of high-minded ideals is at odds with cultural protectionism, and while the latter is bigoted and small-minded, it also winds up having the virtue of forcing newer immigrants and minorities in general to conform to American cultural norms (including those high-minded ideals). I think Bouie is a bit harsher than necessary to Douthat, who isn't exactly warm towards those who he says use discrimination and persecution to get their way. But I also think Bouie is correct: Douthat's claim that it's the nativists who have indirectly encouraged assimilation through intimidation may not be entirely wrong, but it's a somewhat strained reading of history -- the nativists didn't want assimilation, they wanted (and often got) exclusion. And Bouie is right that Douthat's history ignores that those in Douthat's "first" America (the one with the high-minded ideals) have almost always supported and worked to achieve assimilation.
But I think both of them are missing the main actors here: the immigrants themselves, who in almost all cases have been pretty desperate to assimilate as quickly as possible. That was true of the great immigration waves in the late 19th and early 20th centuries, and it's true of the great immigration wave now. Of course, each group has had various cultural bits and pieces they keep with them (bits and pieces which generally are gobbled up by the larger American culture, so that everyone eats tacos and bagels), and each group has minorities within their minority who resist assimilation, keeping the old language and practices alive (although often radically altered, sometimes without anyone realizing it) even as most of the community drifts -- runs -- towards America.
Of course, assimilation isn't always benign. Often, assimilating American ideals means assimilating American bigotry -- see for example Michael Rogin's Blackface, White Noise. I'll also use the excuse to link to Martin Scorcese's wonderful Gangs of New York, since it covers a lot of the themes in these arguments.