For a few years at the beginning of the decade, the banjo and the acoustic guitar unexpectedly became fixtures on Top 40 radio thanks to bands like Mumford & Sons and the Lumineers. In many ways, these groups were following a path paved by Virginia's Old Crow Medicine Show, which had begun bringing old-timey bluegrass and country music to younger audiences in 2004 with its debut album "O.C.M.S." The album contained the group's biggest song to date, "Wagon Wheel," which was built around a Bob Dylan lyric and taken to the top of country charts by Darius Rucker nearly 10 years later. Since then, Old Crow has co-written a song with Dylan and been inducted into the Grand Ole Opry.

amNewYork spoke with co-founder Ketch Secor as the band prepared for a tour with Willie Nelson.

You pre-dated the roots music revival. Were you surprised by its success?

Roots music comes and goes in waves. We just got a sense of it before the others, and it swept us up in the late '90s. I always felt born to play folk music, just like its power-to-the-people mentality. I've been a rabble-rousing peacenik since I was a kiddo.

How did you first get into string band music?

I wanted to play the banjo just like Happy Traum did on a recording I loved of Bob Dylan's "You Ain't Goin Nowhere." Bob Dylan inspired me to keep following the breadcrumb trail back to the source of his own canon of song. When I got up to the headwaters I was a changed man.

What was your reaction to Darius Rucker's version of "Wagon Wheel?"

Darius is a great guy. He sings it sweetly and stays true to the nature of the song. He first heard it sung by a group of teachers at his daughter's school. I love that about "Wagon Wheel" -- how you can first hear it from such a natural source. It has never been a "Billboard" kind of a song. Then again Darius sure had a big hit with it, so maybe it has changed since then.

You wrote that song while in high school. What inspired it?

Girls, girls, girls. I needed something to impress the girls.

What's it like to tour with Willie Nelson?

Willie is the last of the American cowboy singers. ... He played with the greatest voices of his generation -- country music's greatest generation -- wrote the songs that brought them to incredible heights, and through his own maverick maneuvering managed to become greater than them all. It's the high water mark of 16 years in the music business for Old Crow to be circling the wagons with Willie this summer.

Old Crow Medicine Show (with Willie Nelson & Family)  plays Celebrate Brooklyn @ Prospect Park Bandshell (enter at Ninth Street and Prospect Park West. ) Aug. 12 at 7 p.m. Sold out.