Ricardo900 said:not necessarily, people will use both "I'm American" or "I'm from the USofA", when I travel overseas, I would tell people that I am American, because hopefully they would figure out that Americans are from the USofA, so there's no need to say the entire country when asked.
The same for "Soy Dominicano" or I'm German.
Of course, Ricardo. I myself at times answer to the question "where are you from" with a "soy dominicano" and other times with a "I'm from the Dom. Rep."
But then again, the question is where are you from, not what your nationality is. It's subtle and it may not have great importance, but "where are you from" asks for where you where born, so you 'need' the name of a geographic place in the question. Saying your nationality works just fine too.