I would also add that you will find a wide array of subcultures within the United States, it all just depends on where you go. Big cities, small towns, midwest, northeast, south, etc...the personalities of the people that make up these regions tend to vary quite a bit. Some areas have more friendly family oriented people, others have more loud and aggressive types. It's hard to lump 'America' into one pot, as it does vary quite drastically. And Hollywood does NOT give you an accurate depiction.
Having lived in Miami for quite a while, which is a fairly international city, I've encountered quite a few people from all over the world. A few observations:
-I've noticed that the hispanic people down here (cuban, venezuelan, dominican, nicaraguan, puerto rican, etc etc) tend to be much more loud than everyone else (especially males)). Same thing with the Hatians and Jamaicans.
Having spent most of my life previously around midwesterners (who are probably more reserved as a whole), it was quite a culture shock to move to Miami. But I learned to love the diversity despite my SA.
-The common greeting here in social situations tends to be a kiss on the cheek to females, and often a bro-hug between guys. I'm still not used to the cheek-kiss. I absolutely dread it. (My sister married into a family with Italian heritage, they tend to do the cheek-kiss thing too).
-We get a lot of people from Quebec and European countries as well. I've noticed these people tend to have a much different definition of 'personal space' than do Americans. For example, sometimes in the grociery store, a family of tourists from one of these countries will get right in my space while waiting in line. Americans tend to give each other a little more personal space.
-Another example of how things vary from region to region in the U.S. Miami has the worst drivers in the entire country, rude, aggressive, just horrible. As opposed to other places I've lived like Nebraska and Georgia, where driver courtesy is usually much better. (I've heard horror stories about NYC drivers as well.).
I have to wonder as well, if we get more North Americans on here because of the increasing awareness of social anxiety disorder in this country over the past 10 years. Paxil had quite a marketing campaign going for a while which probably really helped, and certain high-profile athletes and entertainers have publicly brought up their SA. Is it possible the awareness level in certain countries is lagging behind?