Well, I would say as someone who has lived in California, Connecticut, and Louisiana and has traveled to the MidWest alot, that the cultures within the United States differ greatly from area to area. Moving from West Coast to East Coast was a total culture shock! I was considered rude for hugging people the first time I met them, most people smoked cigarettes, people thought I was rude for correcting grammar and mispronunciations (which in my area of California everyone does this and it is considered courteous), it was foreign to me that people wore pajamas outside to check their mail and go to the grocery store, they also had a lot of nomenclature that I have never heard of , people were WAY WAY more into sports and tanning, and the list goes on and on.
I would say that each area of the U.S. has a distinct culture and I would say that each area is maybe a melting pot of the people in that area, but not as the U.S. as a whole. I would say that the morals differ from area to area, customs, and culture.