Blues Traveler has spent more than two decades learning the ropes of their blues-rock role. The current iteration of those lessons can be seen tonight at the Briggs & Stratton Big Backyard, but frontman and harmonica virtuoso John Popper wants his fans to know that Blues Traveler is still very much a work in process. The band, formed in 1987 in Princeton, N.J., may be best known for its improvisational shows and ongoing segues from song to song, a characteristic remaining from its jam-band beginnings. They’ve also gained a radio following for hits like “But Anyway,” “Run-Around” and “Hook,” many of which prominently feature Popper’s vocal and harmonica stylings.

The lineup, featuring guitarist Chan Kinchla, bassist Tad Kinchla, drummer Brendan Hill and keyboardist Ben Wilson, has remained relatively stable over the years. Popper’s own struggle with obesity, his emergency heart surgery and the death of former bassist Bobby Sheehan from a drug overdose in 1999 did little to stall the Grammy Award-winning band’s ongoing development.

Blues Traveler’s most recent album, North Hollywood Shootout, released last August on Verve Forecast, features Bruce Willis. It marks the latest in the band’s ongoing development, lessons Popper says they are all still learning.

“You have to be smart enough to know that you don’t know what you’re doing, and so you give it your best shot by trusting your instincts,” Popper writes on the band’s Web site. “The great thing about knowing that you don't know what you’re doing is that there’s more to learn.”