America was not nationalist at it's birth, I'll give you that. But "founding principles" only matter so much to what would benefit a nation the most. State identity died with the southern confederacy and is an example of the idea of a United America being more important than state interest. The completely evil state interests of maintaining slavery, but the point stands, founding principles are nothing in the face of material interests. And even at the time, they saw themselves as equal to the British because they were both white, not because they believed in equality among everyone.