>>12
To expand upon "accent", it is still a term that is relevent, because people with a certain accent "sound" like they're from New York, Queens, Boston, etc because when they talk in different "communities of practice" hey still sound like a person from those areas.
But saying American has an "accent" on the whole is pretty daft. That being said, as a foreinger, I think the most recognizably "Amcerican accent" is the mid-west one. There is still no such thing as an American "dialect" though, firstly because, as I said, there's too much variation throughout the country and secondly, it's a dated term in linguistics.