Not necessarily true,
>>11! Even amid sections of America, one can find immense cultural diversity. For instance, I find myself privileged(?) to live in a rural cultural hub of ever-present change. My small town, in which I grew up, takes on more and more city-folk moving for cheaper abodes while still commuting back to the city for work as well as tourists in every season.
Meanwhile, locals like myself retain the values we grew up with, often coming into conflict with the city travelers. The younger among us especially find themselves in the minority, which is odd since this is where we're from. I'm at a weird age where I started off with the dot-on-the-map folks and grew with the area, graduating high school with most of my graduating class actually from surrounding areas.
Mind you, this serves as just one example, albeit a very specific one. Any culture has its pros and cons, and lumping one nation into a generalized mold neglects the richness of the diversity on which it was founded. Different regions are extremely dissimilar to where we create the stereotypes we find ourselves battling. Therefore, we should respect, recognize, and celebrate that which makes us different rather than getting rid of that wonderful difference. There are far more dangers in similarity and ignorance than people seem to be willing to notice...