Southern dialect in Texas

[Catlady (Rita Prince Winston)]

"Amanda Geist" <editor at ...> wrote in
<http://groups.yahoo.com/group/HPFGU-OTChatter/message/33226>:

<<  I later talked to a linguist who had studied Texas dialects (Guy
Bailey), who told me that the Southern dialect had been dying out in
east Texas - dying out in general, but retreating from there - for
years.  He said the dialect maps were made from interviews conducted
in the 50s and 60s, when a large proportion of people who were
contemporaries of my grandmother were still around; but subsequent
generations do not have the dialect. My grandmother's generation was
the last to have it in any significant proportion.  The dialect maps
are a picture of an earlier time. >>

Are there theories of why the Southern dialect faded from East Texas?
   I suppose all fading of regional dialects is encouraged by
television spreading one dialect nationwide and by people moving from
place to place a lot, but is there a more specific reason for this
more specific fading? Is it connected to the rise of Houston as an
economic and cultural center as New Orleans and Galveston faded as
economic centers?