Do you mean the Native American Indian? Because the rest of the United States is composed of people who immigrated here.
Early immigrants were English and German, they brought their own customs. We have no native culture that has survived, in fact the Native American cultures were derided and serious attempts at eliminating their language and customs were tried.
Every other culture, has imposed its customs on ours. From Christmas trees to fireworks, to pizza and spaghetti.
The American culture is one of additions and overlays.
And it has nothing to do with liberals. It has to do with history.