Totally agree, the definition is complicated and subjective! Really more of a spectrum than a clear binary. You could certainly argue that the US has a "shared

Totally agree, the definition is complicated and subjective! Really more of a spectrum than a clear binary. You could certainly argue that the US has a "shared history" that unites its various ethnic groups, thereby making it a single nation. Or you could argue that different racial groups and immigrant communities have had sufficiently distinct experiences that they shouldn't be lumped together.