I have posted these comments before, but I'll do so again now.
A word about 'culture'...
In the USA, as has been pointed out, we don't have a thousand-year history of being any one thing. Our ancestors came from all kinds of places fairly recently. We brought with us many customs, traditions, heritages, languages, and everything. We didn't come here en masse, we came in waves, and often driven by economic necessity or a desire for a better life or to escape repression of one sort or another, real or perceived. Some came as slaves, some as indentured servants. Very few of us are actually descended of indigenous peoples of North America.
As our ancestors came here, some assimilated into the majority population quickly; some less so. Some found quick acceptance and were welcomed into the majority population and some did not. Some were excluded due to their religion, their skin color, or their traditions, which were seen as not a close enough fit to the majority to be allowed to join the mainstream. Some chose to exclude themselves for various reasons, including a desire to remain culturally intact, to preserve their language, religion, skin color, or other reasons. This was a continual ebb and flow, and was different in different parts of the country, and in different times as the nation grew.
America is often described as a 'melting pot', but it is not. Melting pots make things that are homogeneous. A melting pot of carbon and iron makes steel; and all the steel in that pot is the same. Anything that is different is 'slag' and is removed.
We are not a melting pot. We are a pastiche. We are a tapestry, a gumbo, a stew. Some things are blended, some retain their individuality to a greater or lesser extent. Some lose their individuality entirely and become just part of the larger mass, indistinguishable from anything else, but other things keep an identity that is flavored by the rest, and lends its flavor to the rest, but still remains distinct and identifiable.
From time to time, usually during times of distress, cries arise for us to return to our cultural roots, our group heritage, our basis. But we don't have one, as many have pointed out. We never had one. We are mostly white, mostly Christian, mostly this or that, but we are not any one thing and we never were.
What is often meant by these cries for a return to a base state is that the person making the demand wants a return to the state THEY are most familiar with. If they are white, Christian, middle class, have a spouse and two kids and a mortgage, they might find a lot of people nodding their heads in agreement with them; but they do not represent everyone. And while they will pay lip service to certain concepts of individuality, pride in origin, or even civil liberties, essentially they are willing to sacrifice those things in order to calm their fears that their culture is going to be destroyed. Note that I said their culture, not our culture. Because it is theirs, not the nation's. The nation doesn't have a culture.
And ultimately, when it is pointed out that there are many insular segments of society whose culture differs greatly from their own, yet they do not complain about those groups, the person making the complaint will explain that they only mean those groups that refuse to assimilate with the rest of us who mean us harm. How they can distinguish those who mean us harm from those who do not and extinguish the civil liberties of only those groups seems to escape them... The only such attempts that have been made in our history have uniformly been things we have come to be ashamed of later, such as anti-Catholic, anti-German, anti-Chinese, anti-Japanese, anti-Jewish, and anti-whatever laws meant to 'force integration' or 'put down a threat' to our claimed mutual heritage. Each time we do it, though, we ignore history and pretend that this time is different. Yes, it was bad to put Japanese-Americans in concentration camps. But no, putting Muslim-Americans in such a camp isn't a bad thing because they really represent a threat to all of us.
They will say they are in favor of democracy; but if a community somehow manages to gain a majority of citizens who are of a different belief or race or religion or ethnicity or cultural heritage and then manages to pass laws that reflect this, they are against it. If they believe in democracy, they should not be.
Take for example the notion that at a certain point in time, the majority of people in the United States will have an Hispanic heritage and speak Spanish as well as (or instead of) English. Even if true, the notion of democracy would support this; what is the difference if the National Anthem is sung in English or Spanish, so long as it is sung, and the rule of law based on our Constitution continues?
Certainly, laws can be put into place by the majority now to attempt to slow or stop changes such as these from taking place. But limiting immigration or requiring English as the national language or restricting 'dangerous' religions or 'hate speech' can only stop perceived threats from outside; it cannot stop changes that come from those who were born here, those who change their views after they get here, or those who are simply thought of as representing a threat.
We are not a single culture. We have a majority, but that doesn't make it the only culture, the only history, the only outlook, the only religion, the only way. We do face threats, but the solution to such threats to our liberties doesn't seem to me to be to dismantle those liberties in the name of saving them. What unites us not the degree to which we assimilate, but the degree to which we defend the precepts of liberty and the structure our nation is based upon. Worship whomever you like; speak whatever language you want; eat whatever foods you prefer; sing whatever songs you find entertaining; dance your own dance, wear your own clothes. Just live within the framework of laws and liberties that make us the USA. That's what being part of our culture means, and that's pretty much all it means.
There have been cultures that defined themselves as a 'melting pot' and then tried to be a single homogeneous thing - one brand of steel, for example, instead of a crazy-quilt of different cultures. Do we want to be like the most recent nation that tried that?