The last time singer Grace Potter had an extended stay in D.C. was for President Barack Obama’s inauguration in 2009.

“I just fell in love with the city: the energy, the food, the houses, the shopping, the people, the weather — all of it,” says Potter, who’s in town this time playing four sold-out shows at 9:30 Club with her band, the Nocturnals.

“It’s an electrified place,” she says of D.C. “No matter what’s happening politically.”

Earlier trips to the District were not so warm and fuzzy. Before Potter, 29, was a glammed-out rock star, she was a student activist attending St. Lawrence University in New York. At 19, Potter came to Washington and was arrested at the 100,000-person protest against the invasion of Iraq on Oct. 26, 2002.

“That’s how I discovered the city. A lot of times, when I’ve been in D.C., I’ve been in trouble,” Potter says, before noting that “trouble on stage is very different than trouble on the streets.”

Potter and the Nocturnals will bring their 2012 Roar Tour to a close with this mini-residency at 9:30. The tour has been in support of Potter’s fourth album, “The Lion The Beast The Beat,” which marks a distinct transformation the Vermont native has undertaken since her 2005 rootsy debut with the Nocturnals, “Nothing But the Water.”

The group started out playing afternoon concerts in open fields as part of the jam-band festival circuit alongside such hippie-friendly groups as Widespread Panic and moe. Potter’s soulful, sultry vocals and the Nocturnals’ loose, improvisatory nature quickly earned the group a cult following, and soon they were opening for established bands such as Gov’t Mule, the Black Crowes and Dave Matthews Band.

The band’s sound continued to develop on 2007’s “This Is Somewhere” (released on Disney subsidiary Hollywood Records) before 2010’s self-titled effort catapulted them into the mainstream. The poppy rocker “Paris (Ooh La La)” and the sentimental “Tiny Light” helped earn Potter a spot on 2010’s VH1 Divas show, alongside Katy Perry, Nicki Minaj, and Ann and Nancy Wilson of Heart.

It also rolled out a new, sexier Potter — one with long, blond hair and short, sparkling dresses. Potter insists the image change was just dress-up, but it was certainly a striking makeover from the flannel shirts and hippie dresses she wore in the band’s early years.

Potter would reach her biggest audience yet in 2011 in a duet with country superstar Kenny Chesney on his platinum-selling hit “You and Tequila,” which earned her the opening slot on Chesney and Tim McGraw’s arena tour last summer.

Released in June, “The Lion The Beast The Beat” reflects almost every aspect of Potter’s career. It’s an eclectic disc with shades of jam-friendly rock (the title track), radio-ready pop (“Stars”), haunting blues rock (the Dan Auerbach-assisted “Loneliest Soul”) and country-flavored balladry (“One Heart Missing”).

It’s Potter’s best bid yet to be everything to everyone — a necessary skill out in the mainstream.

“It’s no fun at all to be the queen of country or the princess of the jam-band world,” she says, before clarifying: “Well, I don’t want to be a princess of anything. I’d rather be king.”

Potter understands she has different audiences now, and she appeals to them with something held over from her jam-band days: the idea that every concert is a new experience.

“What I’m good at is assessing an audience and recognizing what is missing from [a live] experience,” she says. “So, if it’s an audience that reads People magazine and wants to get a little gossip, maybe I’ll give them some fun fodder with an anecdote. If it’s an audience that wants to get down and rage, Neil Young and Crazy Horse-style, that’s where I’m going to go.”

Potter’s never ditched her roots, and the band makes annual returns to many of the festivals — such as Bonnaroo, All Good and Mountain Jam — that supported the band early on. “We are such [expletive] hippies,” Potter says of herself and her bandmates. “There’s no getting around it, that’s just who we are.”

That’s part of the reason she wanted to do four nights at 9:30 Club: to give fans as much of her catalog as possible. She’s even taking requests for each night’s set via Twitter, @gracepotter.

“Four days of music is a way of giving people a sustainable experience,” she says, “as opposed to one night, where they’re like, ‘What happened? That night, man, it seems like a blur.’ ”

Inside Tracks

‘Paris (Ooh La La)’
One of Grace Potter’s biggest hits came from her own musical insecurity and a desire to “figure out what kind of guitarist I wanted to be,” she says.

‘You and Tequila’
This duet with Kenny Chesney put Potter on the country charts, crossing her over to a whole new audience. It’s a somber yet catchy ballad, which shows her diverse talents.

‘Loneliest Soul’
The chugging drum beat and haunting vocals should clue Black Keys fans into the presence of guitarist Dan Auerbach, who produced and co-wrote this track.

‘Nothing But the Water’
Potter’s signature, gospel-tinged song from the band’s debut disc is still the biggest show-stopper during concerts.

9:30 Club, 815 V St. NW; Thu., 7 p.m., Fri. & Sat., 7:30 p.m., Sun., 6 p.m., all shows sold out; 202-265-0930. (U Street)