As an anecdote, I've lived the majority of my life in America (born and raised middle class on the east coast in a wealthy area) and if I was tasked with writing an account of my time here it would be focused around one thing: alienation.

American life is atomized and consistently getting more so. For anyone who sits around and thinks about why people are the way they are here I highly encourage you to consider that people are alone. Alone in life, alone at their apartment, alone when they struggle, alone when they die. It's to the point where we regard married couples that live a 20 minute drive from anything as not being alone when they really are.

Most adults I know have a relationship with their immediate family that I would regard as acquaintanceship.

Part of this is culture (Americans fetishize a sort of "rugged individualism" where you alone can solve every problem you're faced with or else it's not a real problem) and part of it is civil engineering. You need a car to live nearly everywhere, there's almost no public transit infrastructure, etc.

EDIT: Since this is popular I wanna surface something that people have been saying: it definitely doesn't require being far away physically from others to feel alone. I live in Manhattan and big cities can be extremely alienating depending on the person.