Newcomers still get much of the blame. In the past decade the South has seen an unprecedented influx of immigrants from both other states and other countries. The population in the south grew by 14.3 percent from 2000 to 2010, making it the fastest growing region in the country.

But there is more behind the social shift, scholars say. Digital communication and globalization have conspired to make many parts of the South less insular. Couple that with a political climate as contentious as anyone can remember and a wave of economic insecurity rolling across the region, and you’ve got a situation where saying “thank you, ma’am” isn’t good enough anymore.

“There are just so many more complexities,” Mr. Wilson said. “Manners and a code of civility can’t help you negotiate everything.”

Some say the South’s great cities seem to be losing civility faster than country communities, where stopping to ask for directions can still end in an invitation to supper.