Go-go band Rare Essence performs at SXSW. (Courtesy of RAW Entertainment Films)

AUSTIN — It’s a Tuesday night deep in the heart of Texas, and Rare Essence bandleader Andre “Whiteboy” Johnson is all smiles.

“We’re just amped about this thing,” Johnson says backstage before one of his band’s most far-flung gigs. “We’ve done some other festival-type things, but nothing like this.”

This is South by Southwest, the annual music, film and technology mega-conference in Austin — a massive gathering where entrepreneurs, tastemakers and assorted creative types come to schmooze, ­self-promote and get their brains rearranged by new music. Rare Essence is eager to help out with the ­brain-rearrangement part. The legendary Washington troupe is about to become the first go-go band to ever perform at SXSW.

The group is here to formally evangelize for its home town, too. Tuesday night’s musical showcase is presented by the D.C. Economic Partnership, a nonprofit group working on behalf of the city in hopes of persuading tech entrepreneurs to set up shop in Washington. After first establishing a formal presence at SXSW back in 2013, the city devoted roughly $350,000 to to this year’s efforts, which included a “We DC” lounge that hosted five days of panel discussions and parties.

Musically, they couldn’t have booked better ambassadors than Rare Essence — and organizers did a fine job reflecting the city’s musical diversity, too. Tuesday night’s bill also included the rhythm-heavy soul of Black Alley, the glossy indie-pop of Prinze George and the cerebral hip-hop of Oddisee.

“We’re trying to present D.C. in a different light,” says Julie ­Weber, marketing and communications director for the D.C. Economic Partnership. “We’re trying to put the message out there that D.C. is open for business on every level.”

Then Weber zips toward the stage where she gives a hoarse and enthusiastic introduction for Paperhaus, an indie quartet whose bandleader, 27-year-old Alex Tebeleff, is a D.I.Y. rock promoter who hosts regular concerts in his Petworth home, also called Paperhaus. Tebeleff is a mover and shaker who has done plenty to enrich the local underground rock scene, and he says has no plans of slowing down — so long as he can pay the rent.

And that’s the uncomfortable question floating through this particular patch of Texas air: Will Washington’s continued economic growth continue to put the squeeze on our city’s musicians? As pristine condos continue to spring up across Washington like expensive weeds, the ever-increasing cost of living has made it difficult for many musicians to stay in town. One of tonight’s acts, piano-pop trio Jukebox the Ghost, formed in Washington, but left the District in 2007 in search of cheaper rent. (Weber says this issue is a “major conversation piece” that she hopes to see advanced before next year’s SXSW.)

As the clock ticks toward midnight, big men with big drums start crowding onto the relatively teeny-tiny stage. Most of them are sporting candy-red polo shirts and milk-white slacks. One fan, presumably a native Washingtonian, cuts through the thickening crowd shouting a warning to the uninitiated: “It’s about to get live in here, Joe! Y’all are not ready for this!”

The moment the drums kick in, this thing instantly becomes a Rare Essence show. The band works like explosive clockwork, congas and timbales weaving a rhythm that’s as pummeling as it is undeniable. Out in the crowd, hands fly skyward. Butts shake every which way. Newbies become converts. To confirm it, the band closes its set with front-line vocalist DJ Kool performing his call-and-response anthem, “Let Me Clear My Throat.” It sounds like an ecstatic shouting contest.

The sound carries out of the venue and across the street, where two dormant construction cranes loom over an unfinished mixed-use condo building.

It sure feels like home.