BBC4 showed a great 9-part (!) series on Country Music from the mid-20s to the mid-90s (and a bit beyond) over the past month. Must have been a while in the making as Merle Haggard passed years ago and was quite chatty despite that. Probably the earlier years came as more of a surprise. But to relate the saga of Johnny Cash without mentioning the legend of his redemption in Nickajack Cave tells its own story. Otherwise a lot more definitive than some others I could mention.
BBC Scotland ran a nice little series about the characters around Norn Iron's country scene, called "Keepin' 'er Country", looking at truckers, livestock shows, pretend cowboys, priests etc: