Fourty years ago I could tell where any Texas native I met came from within 50 miles based on their accent. The accents were so different that, for instance, thse with a 'Brazos Bottom' accent from 50 miles Southwest of Houston and those with a 'Galveston' accent from 75 miles to the Northeast of there found it very difficult to understand each other.
All that is left of Texas accents, or Southern accents, is a tiny whisper of what they once were.
That is why Southerners and Texans almost always laugh at movie accents.
So9
Even a South where most folks sound like Kansans or Indianans may still be filled with Southerners.
No kidding! When Meryl Streep was all the rage because of her ability to "capture accents," I was gagging. Her southern and Texas accents sounded like nothing I had ever heard.Then there are phony Texans, like Ann Richards, who think that her exaggerated Texas accent plays well amongst the rural folk. In fact, her phoniness is one reason that she's out of a job.
They are getting better though. It used to be so bad---I'd cringe when a "Texas Awl Man" came out talkin' like he just came off a Georgia plantation. ("Now look heah")