Who cares?!?  Well, lots of folks do.  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, 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, "A Rose by Any Other Name"). You wouldn't want to tangle with him. 

Sign found along the AT near Harper's Ferry, VA. Photo Credit - David Tarasevich, Appalachian Trail Conservancy

In other words, the pronunciation has become a modern-day shibboleth (for the origin of this term, see the Old Testament book Judges, chapter 12, verse 6). Another example is the state of Nevada: residents and natives say Ne-VAD-a, but almost everywhere else one hears Ne-VAH-da.  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 almost 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.

So whose side are you on?

Ivey, Mike. 'A Rose by Any Other Name is a Damned Brier'. Appalachian Heritage 14(3): 53-54.

Puckett, Anita. 2000. 'On the Pronunciation of Appalachia'. Now and Then: The Appalachian Magazine 17: 25-29.

Walls, David. 'On the Naming of Appalachia'.