Ashort essay in english comparing and contrasting expressions of greeting and leave-taking used in spanish-speaking countries and in the united states.

There is a lot of similarities between greetings in the US and in Latin America, as probably the most common greeting is "¿hola, qué tal? " which means "hi, what's up". 
It can actually be "strengthened" into "¿hola, qué tal?¿cómo estás? "- which repeats the question of "how are you" twice in two different ways -in fact, which was the most common greeting I heard in Mexico. 
Some regions in Latin America also have their own, special greeting, for example in Mexico you an also hear ¿qué onda? which is no heard in other places, it literarily means "what a wave"! or "what is the wave bringing"