Pronouncing Appalachia (AppaLATCHa)

A very good friend of mine whose family tree is rooted deep in the Appalachian Mountains near the Shenandoah N.P. told me that it is only in the last 10 years or so that he has noticed an increase in the number of people using the northern pronunciation of “A-puh-LAY-chuhn.” He said that the pronunciation of the name is an immediate indicator of whether people actually are Appalachian people to those who have lived there for generations. It is not a reason for prejudice, but it does tell him, in his words, who the pretenders and posers are.  
Although we can all agree that the Appalachian Trail is a beautiful, wondrous footpath that extends nearly 2,200 miles from Georgia to Maine, when it comes to something as basic as to how it’s pronounced, the room is split.
Conventional wisdom says that the Mason-Dixon line represents the division amongst the two common pronunciations, with northerners saying “a-puh-LAY-chuhn”, while southerners say “a-puh-LATCH-uhn”, but conventional wisdom must be taken at face value.
In fact, some people would say that, if you come to the region and say "Ap-pa-LAY-cha," you might as well turn around and make tracks to wherever you started from. In a short essay published 30 years ago in Appalachian Heritage, (A Rose by Another Name is a Damn Brier) one Eastern Kentuckian wrote, "What I finally came to understand is that AppaLAYcha does not exist. At least, it doesn’t exist in the real world. The AppaLATCHans exist; even AppaLATCHa exists. But AppaLAYcha is a fiction. It is an idea created by politicians and reporters" (see below for the entire piece).
As noted in the essay, the name Appalachia is derived from a northern Florida Indian tribe, the Apalache Indians. And there is a Florida town named Apalachicola. I’ve lived in Florida most of my 63 years and I’ve never heard anyone pronounce either the Indian tribe name or the town with the abominable ‘lay’ sound. The Indian name is pronounced “ApaLATCHe” and the Florida town is pronounced “ApaLATCHicola”
For many in the hills, the choice of vowel sound marks whether you're an insider or an outsider (see Anita Puckett's essay below). It's not clear how or when folks in Washington and elsewhere came to view Ap-pa-LAY-cha as the "right" pronunciation, because Ap-pa-LATCH-a certainly reflects the original vowel. David Walls has searched old maps and found a related term used first on Spanish maps of the mid-16th century.

A Rose by Another Name is a Damned Brier
https://artsandsciences.sc.edu/appalachianenglish/sites/default/files/Ivey%201986%20-%20A%20rose%20by%20any%20other%20name%20is%20a%20brier.pdf

Pronouncing Appalachia by Novelist Sharyn McCrumb
https://www.youtube.com/watch?v=eGCqWrsAZ_o