Naturally Russian people are taught to smile when greeting foreigners - when you do not know a person suspect the best. That can be taken for controlling emotions. But the situations of fear or anger are quite different. People are encouraged to show the emotions they feel and this is not considered to be bad in Russia. Myths are still very strong:)

American culture was profoundly influenced by the inflow of non-English speaking immigrants between 1880 and 1920. Given that facial expressions are universal, what better way to counteract xenophobia between people who don't speak the same language than to readily show a very broad smile to strangers? At the turn of the last century, roughly 3 out of 5 New York City residents were non-native born. Suspicions and prejudices weighed heavily against cultural assimilation that occurred, nonetheless, over the first half of the 20th century. A big, ready smile may have gone a long way toward managing nativist suspicions and xenophobia among so many persons of varying backgrounds and languages.

Perhaps one legacy of this history is the American tendency to readily display emotions nonverbally, and in particular, the broad ‘American’ smile.