In May, Jerry Douglas, who has been called the Jimi Hendrix of the dobro guitar, was traveling with Alison Krauss and her band, Union Station. They were on the Great High Mountain Tour, an amalgam of roots and old-time music concerts produced by the legendary T-Bone Burnett. Near the tour’s end, the group played the Beacon Theatre in New York City. The program featured many groups, but the popular stars were clearly Krauss and her band, including Douglas, whose musicianship mixes the warmth of porch music, the spontaneity of jazz and the blazing licks of rock.

Even if fans aren’t exactly sure what the dobro is, they know Douglas, a headliner at the 66th National Folk Festival, because he has been showing up in bands since the 1970s. He started playing the instrument as a boy after his father, a steelworker and bluegrass musician in Ohio, took him to a concert featuring Lester Flatt and Earl Scruggs with the Foggy Mountain Boys. The legendary Josh Graves and Oswald Kirby were playing dobro. From then on, Douglas knew what his calling was and listened to it.

In June, the National Endowment for the Arts awarded Douglas a 2004 National Heritage Fellowship, the country’s highest honor in the folk and traditional arts. That makes it official: He is a national treasure.

“It’s like being a singer,” said Douglas of his early attraction to the dobro. “That’s what made me want to play it in the first place. I was a singer, but when I started playing, I stopped singing as much. I can play the guitar and other string instruments. I’d love to be able to play the piano, but I can’t – yet. But the dobro does everything I want.”

The instrument was invented in the 1920s as a way to increase the volume of a guitar so that it could stand up to horn sections in bands. Played horizontally, it is fretted with a steel bar, or slide, in one hand while the fingers of the other hand pluck the strings. The sound is similar to a Hawaiian slack key or a lap steel guitar, which makes it perfect for the twangs of country and bluegrass music.

But Douglas has, notably, taken the dobro to new dimensions. Indeed, when he started playing the dobro, the instrument hadn’t shown up in rock or the blues. It was as if it was waiting for an innovator, the same way the electric guitar was waiting for Hendrix. As a testament to Douglas’ place in the dobro world, Gibson has named a mahogany signature artist instrument after him.

Douglas is best known these days for his membership in Krauss’ band. He also is featured on the “O Brother, Where Art Thou?” recording. He has won eight Grammy Awards, was named the 2004 Best Musician by the Nashville Scene Readers Poll and has performed with James Taylor, Paul Simon, Ray Charles, Garth Brooks, Bela Fleck, Reba McEntire and Norah Jones. He recently made a recording with John Fogerty of Creedence Clearwater Revival, an influential group in Douglas’ own musical sensibility.

Rock ‘n’ roll licks are never too far out of earshot in Douglas’ performances.

“I grew up listening to a wide variety of music, but rock ‘n’ roll was a part of it,” said Douglas, who is 46 and lives in Nashville with his wife, Jill, and three children. “I learned the traditional music, but I had these other influences flying at me at the same time – the Stones, the Beatles, CCR. It’s kind of confusing to me when it comes to putting myself in a genre. It’s become harder and harder to pigeonhole musicians. They listen to a lot of different styles of music, and they all come out in the performance.”

More than the music comes out when Douglas performs, too. Onstage, he looks as much like a dancer as a musician.

“Music should do that,” he said. “It should bounce. It should swing. You can get so involved in what you are playing that you begin to act it out. Does that sound crazy? It’s that it’s not so cerebral that you have to rely on sound to say everything you want to say. There’s something more to sounding musical. You have to live it.”

In June, Douglas was at the Telluride Bluegrass Festival in Colorado. The festival has been going on for 30 years, a whirlwind of musical Americana played to the backdrop of the Rocky Mountains, which is a popular spot for skiers in the winter and, like Bangor, a perfect setting for cool summer concerts. Tickets for the famed Telluride festival, by the way, cost $55 a day or $170 for all four days.

But that’s not what Douglas brought up when asked whether the National Folk Festival, a free event, stood out in his experience of playing festivals.

“It’s just so big and there are so many different kinds of music there from different cultures,” he said. “I know what I’m getting into up there in Maine. The National is more – I won’t say the cream of the crop – though they are. But it’s a popular program.”

While he is often backing someone else’s band, fronting his own trio with Keith Sewall on guitar and Gabe Witcher on fiddle is another reason he is looking forward to the National.

“Keith and Gabe play those instruments, but they don’t think like those instruments all the time,” said Douglas. “They’re crazy. They’re like me – they don’t feel like they always have to play the same thing all the time. We’ll play all kinds of stuff. If we think the audience wants something, we’ll take them there.”