Actually, the original dialect of American English is what is called by some a 'high Southern accent', characterized by Civil War movies in which the Southern generals from Virginia say things like "Miss Scaalet, you aa looking mahty luvly tuhdey...I do hope the guvuhnuh shows up" This is a bad transcription, but hopefully yall can catch my drift. This is the 'proper speech' often heard (less common nowadays) in the legislatures of Virginia and Georgia.
This accent, interestingly enough, comes from lower class accents in England at the time Virginia was colonized. What's funny is that this is probably the closest to Shakespearean English that anyone gets nowadays. If you pay attention, the accent of Liverpool, England, long considered 'low-class', sounds pretty phonetically similar to this 'high southern' accent. If you don't pay attention sometimes, Paul McCartney can sound like he's from Richmond!