Through his lens, he's made epic explorations into "Baseball," "Prohibition" and several wars. Next year, documentary giant Ken Burns will take audiences on a 16-hour journey through "Country Music."

The eight-part film is set to premiere on PBS in the fall of 2019 and has been in the works for six years. It's only the second Burns project to center on a musical genre, following 2001's "Jazz."

So, how did Burns, a self-professed "child of rock 'n' roll," end up in the realm of Johnny Cash, the Grand Ole Opry and Bill Monroe? He points to an anecdote from "Jazz," when Charlie Parker would play country records on the jukebox and tell his bandmates, "Listen to the stories."

"Country music is just the perfect subject," Burns says. "Because as (songwriter) Harlan Howard said, 'It's three chords and the truth.' It does not have the sophistication and elegance of jazz, but what it has is essential human emotions and stories told, basically, that everybody experiences. When someone says, 'I'm not a fan of country music,' we just say, 'OK, just watch.' "

Country artists and the classic songs they wrote and recorded are at the heart of "Country Music." More than 100 interviews were conducted for the project, many of them with prominent country musicians, songwriters and industry figures. The list includes Marty Stuart, Rosanne Cash, Vince Gill, Reba McEntire, Dwight Yoakam, Kris Kristofferson, and Naomi and Wynonna Judd.

Burns says Stuart and Cash have a particularly heavy presence in the film, and the exclusive clips shared with USA TODAY NETWORK illustrate why.

Cash, an accomplished artist in her own right, shares the reason her father, Johnny Cash, wrote "I Walk the Line." And Stuart drives home just how momentous it was for an artist to make it to the stage of the Grand Ole Opry.

"It was almost like a badge of honor that you had to bring your culture with you to the table," he says on screen. "... Willie Nelson brought his poetry from Texas, Patsy Cline brought her heartache from Virginia. I mean, it was the most wonderful parade of sons and daughters of America, that brought their hearts and their souls and their experiences, and it gave us a great era in country music."

The story of country's evolution is a compelling one, too, from its beginnings as "hillbilly music" to its first recordings and broadcasts — and how listeners across the country then took the genre in countless new directions, from bluegrass to western swing and rockabilly.

"Defining (country music) has been something that's been debated and argued about from the get-go, and we embrace that," says Dayton Duncan, the film's writer and co-producer. "Part of our motivation is trying to answer that question, 'What is country music?' I suppose if we have an answer — and I think we're more interested in pursuing that question than in necessarily answering — it isn't a music. It is many different musics."

"Country Music" was directed by Ken Burns and produced by Burns, Dayton Duncan and Julie Dunfey. It will air on PBS in the fall of 2019.

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