Here’s the Appalachian Regional Commission’s list of counties officially considered part of the Appalachian region: https://www.arc.gov/appalachian_region/CountiesinAppalachia.asp
It’s probably fair to conclude that some of these are included primarily for political and/or economic reasons. The highest point in Mississippi is just 807 feet above sea level, so I doubt if many Mississippians think of themselves as “mountain people.” My maternal grandfather was from Lee County, Mississippi.
I’m from Tuscaloosa, Alabama, one of the official Appalachian counties. It’s at low elevation, but there is a strong history of coal mining, which creates a cultural tie: https://blackwarriorriver.org/coal-mining/
I never thought of my area as Appalachian, but my paternal grandfather was from near Bristol, Virginia, which certainly is.
Here are some country music artists from the Appalachian region, and their recent accomplishments, as well as some links to sites covering music in the region:
Kenny Chesney had the top grossing country tour last year, estimated at $114.3 million (per Billboard).
Eric Church had the top grossing country tour the first half of 2019.
Luke Combs moved to Asheville, NC at the age of 8, and is currently enjoying his sixth country airplay number one, and is setting various major records: http://www.cmt.com/news/1810059/luke-combs-breaks-1988-record-set-by-randy-travis/
Chris Stapleton’s “Traveller” album was RIAA-certified quadruple platinum. This is the best selling record in country music for the last half decade or so. He played a few new songs at recent shows, including one with John Mayer. I look forward to seeing Chris and Morgane at Marty Stuart’s CMHOF event next month.
Tyler Childers’ new album debuts at number one on Billboard’s Country Albums and Americana/Folk Albums charts. Here’s a lengthy interview he did with Chris Shiflett’s podcast a couple of years ago: http://walkingthefloor.com/episode-96-tyler-childers/
Jessica Bray’s Kentucky Country Music recently celebrated ten years: http://kentuckycountrymusic.com/2019/08/celebrating-10-years-of-kentucky-country-music.html
In Appalachian Virginia, the Galax Old-Time Fiddlers Convention was a few days ago: http://www.oldfiddlersconvention.com/
Capture Kentucky keeps up with a lot of Kentucky artists: http://www.capturekentucky.com/
Music City Maven recently posted a huge batch of Nicholas Jamerson (of Sundy Best of eastern Kentucky) videos on YouTube: https://www.youtube.com/user/crystal1218
The Crooked Road in southwest Virginia is filled with country and roots music https://www.myswva.org/tcr
Kentucky’s Country Music Highway is practically an extension of the above, and the Highway 23 Country Music Museum is definitely worth a visit.
Dollywood is one of the most iconic places in Appalachian Tennessee. Here’s their entertainment schedule: https://www.dollywood.com/themepark/Entertainment