Last October as the Shotgun Ragtime Band whipped up its Grateful Dead tribute groove for the 173rd consecutive Sunday at the Driftwood Char Bar, a bona fide blues jam broke out, the sort of one-night-only organic happening that's the legend and lifeblood of live music.

As Ragtime guitarists Kevin Wick and Phil Wong kept things chugging along to drummer Steve Fine's and keyboardist Chris "Jazz" Jasperson's rock-solid spine, and as guest guitarists Wain McFarlane (Ipso Facto) and John "Markiss" Marcus (Markiss & Shades of Color) took turns scorching the Fillmore Midwest-worthy posterized walls, Phil Westerberg — eldest son of the esteemed Minneapolis musical family — shimmied off to the side of the band and blew a white-hot blues harp that soared over the Deadheads worming away on the packed dance floor.

What in the name of Jerry Garcia's ghost is this? Big Sur? San Francisco? Nope, just another Sunday night in south Minneapolis — which, at the Driftwood, can often feel like another place and time, thanks to the Shotgun Ragtime Band's marathon sets, which start acoustically somewhere around 6 p.m. and often end, electrically and psychedelically, just before midnight.

"It's like going to church," said Driftwood owner Heidi Fields, standing/dancing in front of the band and surveying the cast of regulars, stragglers, musicians and other freaky found family members.

"I've known all these people for so long. Kevin and Phil were in the first band that played here when we opened in 2007. They were called WickWong and they just came in and we were trying to start music and I said, 'OK, let's do it.' "

Before landing the Driftwood residency, WickWong's crew holed up Sunday nights at its rehearsal space in the basement of the Sparks restaurant in the Bryn Mawr neighborhood of Minneapolis. They played Dead and Dead-inspired tunes, then transported the same freewheeling vibe to the Driftwood. So far, according to all concerned, it's been a perfect marriage between bar and band.

"We only play here, and some festivals," Wick said. "We won't play anywhere else in Minneapolis, unless it's a benefit, because we play here every Sunday. It's a communal system. The bar is a stakeholder; Heidi and [booker] Larry [Sahagian] are as much stakeholders as anyone who plays an instrument, and the people who come out to see us are stakeholders, too. It's a different way of running a band, where it's all about this gig and the community of it."

In keeping with the Dead's bootlegging tradition, tapers and videographers routinely set up near the soundboard, documenting each gig. Some nights, singer/dancer/drummer/tambourine player Elizabeth "Betsy" Malia Wadden sells her jewelry and works a kaleidoscope light that throws trippy patterns on the bar wall's black-light posters, massive sun god wall hanging and a framed poster of nude female backsides promoting Pink Floyd's back catalog.

To that backdrop, on any given Sunday night, the Shotgun Ragtime Band dips into its 400-song-strong catalog and slowly, over the course of several hours, unfurls its Dead scrolls with little eye contact or ego. The band locks in and surfs the same transcendental moments, and while set-lists vary from week to week, hard-core Deadheads can rest assured that holy grails such as "Ramble on Rose," "Shining Star," "Tennessee Jed," "Jack Straw," "Stella Blue," "Terrapin Station" and, yes, "Truckin' " are well represented, along with enough surprises to keep even the Dead clueless happy.

All in all, it's the next best thing to that mythic Dead tribe vibe — at least until July, when the surviving members of the real Grateful Dead mount what they say are their last-ever concerts. But before and after that happens, the Shotgun Ragtime Band will be busy picking up the slack.

"Before every gig, I say, 'What would Jerry do? What would he do if he was playing in Minneapolis, at this bar?' And that makes it wide open," said Wick, noting that on April 19, the band will celebrate 200 consecutive Sundays of keeping the Dead alive.

"The Dead material obviously offers a lot of room, but it also allows us to play other songs, just like the Dead did. We can play anything that comes up."

Band rehearsals consist of each member diligently listening to a recording of the previous Sunday's performance. The list of guest singers and players includes Nicholas David and Javier Trejo, and while the Shotgun Ragtime Band's main thing may be fun and community, it's obviously going for something serious musically — or as serious as the Dead ever did: Hardcore improvisational music that's reliably taut and, for the most part, free from the sort of meandering that gives jam bands a flaccid name.

"For me, a longtime drummer and Deadhead, it's a chance for me to put out the Grateful Dead music and touch that energy," Fine said. "It's a passing of the torch of the Dead experience. There was a real give-and-take between the Dead and their audience, and that's what we're presenting here, because Jerry died almost 20 years ago now, and a lot of the people who come here never got to see the Dead."

Jim Walsh is a writer and songwriter from Minneapolis. He can be reached at jimwalsh086@gmail.com.