The sociological and anthropological ink is bound to flow on this, trying to figger out WHY, but the Social Security Administration reports that in 2006, in 11 out of 13 Southern states, Madison was the most popular baby girl's name.
Madison? In the South?
The most popular baby boy's name during the same period, in 8 out of 10 Southern states, was William. Not Billy, but William.
'Course, we're gonna call 'em Billy anyway.