I guess it’s not a minor 7th, flat 5 then?
Listen to the last verse of David Allen Coe’s “The Prefect Country & Western Song” to know what a country song needs to be about.
How bout this one?
They’re playing electric guitars in both videos. In the first one, Chet’s is designed to retain some of the dimensions and characteristics of a Spanish (nylon-string) guitar, but it’s made to be plugged in for amplification and/or recording. Notice how thin it is. In both videos, the second guitarst is Paul Yandell, who’s playing what I think is the Gretsch Country Gentleman, a semi-hollowbody electric guitar named and designed in honor of Chet Atkins, who’s also playing one in the second video.
Here’s a video of modern bluegrass. They’re paying homage to the man seated in the center, the mighty Earl Scruggs. Bluegrass, which I consider to be within the country genre, has always been about instrumentals. With singing, too, but less of it.
I just thought you were overgeneralizing in saying that Country music is more about the singer than the instruments. I don’t think the instruments typically take second fiddle (heh) to the singing, and there’s plenty of examples of electric guitar in Country.
As for instrumentals, I imagine there are Country instrumental songs out there, just not as many as songs with singing. But I’d say it’s the same with Rock. How many well-known completely instrumental Rock songs are there? A few, but not a ton.
Yes, there are, for instance Buck Owens And The Buckaroos had many instrumentals. And as mentioned above, in bluegrass instrumentals are dominant (and I’m of the same persuasion that bluegrass falls under country music, but that’s a question for another thread).
Here’s a famous one:
Another one:
If you watched the Ken Burns series on country music, he defined that genre A HECKUVA lot broader than I would’ve.
I think this is probably a meaningless attempt to discern a clear distinction. What do you do with a “country rock” band? Lynyrd Skynyrd?
I’m wondering why the OP desires to draw such a distinction? I’m trying to figure out what musical distinctions ARE meaningful? When I was in college, the big “debate” was “What is New Wave?” Heck - I even have a problem with “unplugged!” And how do you define “rock and roll?” Do you define it by the performer? Instrumentation? Individual songs? …
Pretty easy to distinguish music at the extremes as country/not country. But in the middle, there is a ton of overlap. The same tune can be played in various styles and with various instrumentation, which would make it seem like country or not.
When I was younger, I used to say the only music I disliked was opera and country. Now, I’m all about the twang. In fact, my favorite music is past country and into oldtime! 
I used to be in rock bands. Now I play bluegrass and oldtime. The vast majority of all of the songs have the same chord progressions - 1/4/5.
John Lennon said, “If you tried to give rock and roll another name, you might call it Chuck Berry,” but Chuck had country roots. “Maybellene” is a version of a country song (with blues roots), “Ida Red,” a big hit for Bob Wills in 1938. Hank Williams’s “Move It on Over” (1947) sounds a lot like Bill Haley’s 1954 “Rock around the Clock.” It’s messy.
Behold, one of the greatest country music albums of all time!
I don’t desire to draw such a distinction. It already exists. I think that’s clear in the OP, and implicit in most of the answers so far, although just about everyone agrees that there are lots of overlaps and caveats.
Country: Pick-up Trucks, Your Mama, horses, Beer/Liquor
Rock: Hot Rods, Your ‘Baby’, motorcycles, Drugs
Don’t be fooled, also uppers and downers. Ask Johnny Cash. They also sometimes sing about those, like the line with the “little white pills” in Dave Dudley’s “Six Days on The Road”.
ETA: wait, I’m gonna have to correct myself. The line “I’m taking little white pills and my eyes are opened wide” is in the Flying Burrito Brothers’ cover, but not in the Dave Dudley version. But my point still stands. Conclusion: rockers love to sing about illegal drugs (especially in the 60s/70s) while country singers sing endlessly about alcohol, while also taking some of the forbidden stuff on the side and mostly keeping their yap shut about it.
You forgot about the dog running off.
Ah, The Marshall Tucker Band. In my estimation, one of the greats of their era. Ever, really. Flute, saxophone, great guitar and bass playing and vocals. Those guys could really play their instruments. I, certainly wouldn’t call them country and hard-core rockers wouldn’t call them rock. Hence, the term Southern Rock. Outlaws (really “twangy”, sometimes) Skynyrd, Molly Hatchet and, of course, the Allman Brothers Band. All somewhere on that spectrum but MTB and the Brothers were in a class of their own.
BTW, how did that twangy sound become to be associated with western/country music. A few notes played that way has me immediately thinking of cowboys and such.
Having been a Country DJ from 1990-1995, a period in which Country grew tremendously in popularity, I could never figure out the uneven dividing line between Country and Country-Rock, at least as far as radio stations were concerned. For example, Restless Heart had a few dozen Country hits and were well-established. Yet, when they had a crossover hit, “Tell Me What You Dream,” Country stations refused to play it because it wasn’t “Country.” However, we did play Dwight Yoakam’s “Fast As You,” which was a really heavy pounding rock tune if I ever heard one. Dwight (and Garth Brooks, of course) really pushed the envelope.
And made messier by the fact that the whole distinction between “rock”, “R & B” and “country” is just rooted in 50s music executives feeling that white people wouldn’t or shouldn’t buy records by black musicians and vice versa.
“R&B” even was an improvement coined by Jerry Wexler over the former official term “race music”.
Yes, indeed
And prison.
And there is now Country Rap. Our plumber is very into it. It’s darker than a lot of regular Country (not that I would know), and has the “twang”, but it’s very much a thing.