Billy Strings plays Thompson’s Point in the first of two sold-out shows on Friday.

The musical genre that is informally called “jamgrass” – a blend of bluegrass instrumentation coupled with the exploratory practice and two-set concert structure favored by jambands – goes straight to the sweet spot of a market like Portland, where both genres of that mash-up can draw big numbers.

Billy Strings, the biggest jamgrass star in the country right now, played the first of two sold-out shows at Thompson’s Point on Friday, and he likely could have sold out more dates if he wanted to. The festive crowd in Portland was completely buying what he was selling – there were far more smiles per square foot than the average concert audience.

Billy Strings has enjoyed such a meteoric ascent in recent years for a variety of reasons. There are some obvious factors – his boyish good looks and innocent charm, and the fact that he is almost comically proficient at his instrument and matched by a backing band that is every inch as talented. He’s a strong songwriter who is also respectful of his genre’s history, and has also pulled in the communal vibes of the Grateful Dead; there was even a full-blown parking lot scene at the concert not unlike the old “Shakedown Streets” of yore.

Despite this classic model for success, there is a thrilling combination of old and new at Billy Strings concerts. He and his band are steeped heavily in the bluegrass tradition – at Thompson’s Point, they played cover songs by genre luminaries such as Bill Monroe, the Stanley Brothers, and Doc and Merle Watson, in addition to traditionals that predate recorded music. Yet they also deployed a fantastic light show akin to modern bands like Radiohead or Phish, which surely dazzled people driving northbound on I-295 during the concert. The setup included a large screen at the top of the stage, so you could see the musicians’ fingers deftly dance on their frets from the back of the venue.

There is also a dance-party feel to their approach to live music. Though lacking a drummer, the steady thump of bassist Royal Masat’s rhythm kept the beat moving and the crowd engaged as effectively as a drum kit or DJ would. The band even built their instrumental passages into rousing, hands-in-the-air climaxes similar to that which can be found in EDM and rave culture.

They kept this blistering tempo going for much of the concert, but hit interesting pockets near the ends of each set where the improvisation got more spacey.

In the first set, they took their song “Everything’s the Same” for a long drive before segueing into a Willie Nelson medley of “Whiskey River” and “Stay All Night (Stay a Little Longer”), a song by Bob Wills and his Texas Playboys, recorded by Nelson in 1973. In the second set, they made their original song “Hide and Seek” serve as the bread for a sandwich with a cover of JJ Cale’s “Ride Me High” tucked inside. In both cases, these sections were the highlights, grand finales earned through tasteful setlist construction along the way.

Although jam bands going back to the Grateful Dead have always dabbled heavily in bluegrass, which along with jazz and blues is a precursor to the genre, it’s novel to see a bluegrass band work from the other direction and get psychedelic with their old-timey roots.

Billy Strings is a bluegrass artist first, keeping the genre fresh in the 21st century and winning it new converts along the way, even in places where he’s mostly preaching to the converted.