"Sammy's long speech," as his mother Jane Lampton Clemens called it, was acquired from her. Ron Powers in Dangerous Waters: "Jane Lampton was in many ways the feminine version of the son who would in turn render her immortal as Aunt Polly...She was small and red-haired, as Sam would be, with small feet and hands; yet she was a passionate dancer, and her son would be a dancer too. She spoke in the soft, almost mannered drawl that Sam would inherit and use to mesmerize his close-up listeners and his lecture-hall audiences--the drawl that could be mistaken for a drunken slur, and which he once lampooned as 'my drawling infirmity of speech.'" p 32 It may have been Sam's slow, measured speech that contributed to Horace Bixby's agreement to train him as a cub Pilot in April of 1857. I've read somewhere Bixby's reaction to meeting Sam and his drawl was distinctive. From my readings, I would not call Sam's speech a "Southern accent," as much as an idiosyncrasy he aped from his mother. It was simply one of the things he learned at his mother's knee. David H Fears