Sounds of the South

in American Voices 2006
by Guy Bailey and Jan Tillery

The SOuthern accent is widely regarded as the most incorrect variety of ENglish, even among SOutherners. "Fixin' to" is a modification of the ENglish auxiliary system.

"Might could": multiple modals provide Southerners with addiitonal politeness strategies.

"useta": additional modal (useta could)

Labov 1994 'Southern SHift":

From the last quarter of the nineteenth century until the end of WW2, SAE grew and became more uniform, due to urbanization.

Y'all and fixin' to is spreading to non-Southerners.