If there is one thing you can count on in America it's that there are no norms, values, beliefs, habits, attitudes, or standards. They will vary greatly from one end of the country to the next and from one culture to the next. Most people will retain their belief systems when they come here and will naturally congregate with like minded people. That makes it possible to be both American and what ever else you might be. For me, I am American, Cajun, and Pentecostal. My beliefs, values, habits...are formed by these three things the most.
The most popular answer is completely wrong. Values, beliefs, habits, etc. do change from person to person in our culture. But to say there are no social norms completely contradicts the idea behind social norms. Social norms are unwritten rules that everyone in a society lives by. There might not be a reason for the norm but thats just how people of that society live. A good example include that of personal space which americans find very important. Say someone is sitting at the mall in the food court minding their business and eating. Someone comes up and sits down at your table and starts eating, while there are 50 other open tables. That is out of the norm in our society. Another example is bathroom etiquette for males. If there are 5 open urinals and someone comes up and uses the one right next to you, it freaks people out. We encounter thousands upon thousands of social norms everyday. To say there are none is like saying social norms do not exsist.