I have a piece on the home page on the importance of the American cultural nation, in the context of a discussion of civic nationalism:
It is certainly true that different forms of nationalism can be more or less inclusive and democratic. But no nation has ever been entirely civic in this sense, and it’s foolish to consider the United States any different.
Our cultural nation was extremely important at the outset, and remains so today. At the time of the Revolution, the colonists were 80 percent British and almost entirely Protestant. As John Jay wrote in the Federalist No. 2, “Providence has been pleased to give this one connected country to one united people — a people descended from the same ancestors, speaking the same language, professing the same religion, attached to the same principles of government, very similar in their manners and customs.”
The fact is that culture is seeded with ideas. Would America be the same if its people spoke Russian — the language of a country that has never effectively supported property rights, the rule of law, or limited government — rather than English? Would our political culture as we know it have emerged if practically every home in America a couple of hundred years ago had had a Koran on the nightstand rather than a King James Bible? Of course not.
At the beginning, this was a country not necessarily for Englishmen but by Englishmen, including their notions of liberty, which defined the American experience from the outset. Tocqueville famously wrote that the American was the Englishman left alone. If the eastern seaboard had been settled by Spaniards, you could have “left them alone” for a very long time and marinated them in all the Enlightenment philosophers, and they still never would have come up with the American founding.