You're 100% right except in the United States federal law is the supreme law and overall the culture of the United States was designed to be the same although it has lately been fragmented. There are of course some subcultures but nothing like the completely different thinking between nation states in Europe. I challenge anyone to say that the French and Italians and English are the same really in any way oh, because they definitely are not..... and just a quick edit to point out that they each have different immigration methodology and policies