NESTLED HALFWAY between Birmingham and Nashville on I-65 is Athens, Alabama, a small town of about 22,000. It's slow, quiet, and peaceful. Just how Brittany Howard likes it.

"I'm at home," she sighs in delighted, languid relief. "I had a normal day. I'm gonna go to the eye doctor. Just normal stuff. It's lovely."

Normal days, however, are becoming scarce for Howard, who fronts Alabama Shakes, a tightly coiled, searing, soulful rock band who've burst forth from the Bible Belt with astounding force and tantalizing promise. With only a four-song EP to their name, Alabama Shakes are selling out venues in cities they've never played, from Portland to Los Angeles to three straight nights in London.

That they have only four songs is of little matter. The pull of Alabama Shakes' thumping, soul-fire, rhythm-and-blues magnet would be equally strong had they only one tune played for an hour. The band thuds with precise, rumbling force as if fingers and kick drums were lashed together. Howard's voice, meanwhile, belies her relaxed, polite demeanor. It is tremendous, powerful, and evocative, transcendent of question and setting.

As the recently deceased Etta James once told the Los Angeles Times, "When I'm singing blues, I'm singing life. People that can't stand to listen to the blues, they've got to be phonies."

Same goes for Howard, who began playing at age 13 after a fit of boredom led to the discovery of her sister's forgotten guitar buried in a closet. By 2006, her sophomore year, Howard approached Zac Cockrell, a junior who played bass. "It was like a think tank, me and Zac," Howard says. In 2009 they added drummer Steve Johnson and Heath Fogg on guitar. They began mixing covers of Led Zeppelin, the Rolling Stones, and Sharon Jones with a burgeoning catalog of originals.

Athens, however, is a city without a scene. The Shakes reached out to nearby Alabama towns like Birmingham, Decatur, and Tuscaloosa. "We tried to play as many crummy places as we could," Howard says. "We played anywhere that would have us."

There, on tiny or nonexistent stages in dive bars, dodging beer bottles and indifference while making converts, the Shakes cut their teeth. Howard learned to howl above gnashing drums, 300-watt bass amps, and ratty PAs. Over the course of some 100-odd shows, the Shakes were tested. The band chose a studio in Nashville where they could record live, together in a room. The resulting EP is electric.

Last August, Howard was asked for a song to be featured on a Los Angeles blog called Aquarium Drunkard. "I didn't know what a blog was," Howard says. Nevertheless, she acquiesced. "I woke up that next day and my inbox was full of stuff... from people in the music industry interested in meeting us and talking to us," she says. "It was really overwhelming."

The Shakes' good fortune continued when Patterson Hood of the Drive-By Truckers caught a set, then offered opening slots and the Truckers' management. Playing music as a job, something that never previously occurred to Howard, suddenly seemed possible. Last September, albeit with some trepidation and reluctance, Howard quit her job as a mail carrier.

"It took awhile, but luckily everybody just said, 'Let's just try it,'" Howard says. "We're glad we did. I've already seen more stuff than I thought I would ever see in my life."

Despite the sudden changes in her life's trajectory, Howard remains grateful and grounded, at home in Alabama. "I've been a lot of places I really, really like. But when we get home from playing and meeting all these people you just want to do what you used to do."