He announced his U.S. tour in July and booked the E Center in West Valley City. That's an enormous venue for a folkie singer-songwriter who had only one minor hit five years ago, "The Remedy," and even that didn't crack the top 10 in America.

But Mraz knew he could fill the E Center because he knew something was bubbling up to the surface, and it was "I'm Yours," a song he had recorded in his bedroom four years ago. It became the first single off his third major-label album, "We Sing. We Dance. We Steal Things."

In September, "I'm Yours" cracked the top 10 for the first time in the San Diegan's career, and it is a bona-fide hit that your younger sister and grandmother both love.

"I'm glad people want to hear it," Mraz said in an interview. "I didn't sit down and write it thinking it was going to be a hit."

Mraz handed his record label the simple acoustic song about devotion only after the label asked him for some unreleased songs to post on the Internet during the recording of his commercially unsuccessful second album. The track was downloaded by the thousands. "It definitely took on a cult following," Mraz said.

He didn't realize how big the throw-away track had become until he visited Sweden earlier this year and everyone in the audience knew all the words to "I'm Yours."

The song is a typical one for the highly literate 31-year-old musician born in Virginia. Mraz is in love with his acoustic guitar, but draws influences from reggae, jazz and hip-hop, turning his songs into one-man jam sessions when he's alone and psychedelic symphonies when he's backed by a band. He sings lyrics quickly, as if someone has asked him to sing "Peter Piper picked a peck of pickled peppers" as fast as he can.

Mraz spends lots of time alone when he's touring and has used that downtime practicing photography. He's releasing his first book of photography in November, a collection of Polaroid pics taken over the past half-decade during his travels throughout the world. As a measure of his increasing success, the legendary Graham Nash wrote the foreword. Mraz loves shooting Polaroid pictures because they're "very tangible and tactile, and it's not flawless." The flaws illuminate the truth, he said.

Another thing he believes in is opener Lisa Hannigan, whom he hand selected although he had never met her. "I was the one who begged to track her down," Mraz said. "I love turning people on to people outside the U.S."

Hannigan is an Irish singer best known for a long collaboration with Irish singer-songwriter Damien Rice.

"It was so great to get the call to do this huge, crazy tour of America," Hannigan said from Kentucky in a phone interview during an off-day of the tour. She and tourmates were about to "roam the streets of Pig City" looking for barbecue before seeing David Byrne in concert.

Hannigan recently released her first album, "Sea Sew," a collection of beguiling singer-songwriter tunes partly inspired by trips to the Irish coast when she was younger. After performing alongside Rice and many others throughout her career, she said he encouraged her to record her own album so she could perform in "more socially acceptable" venues than pubs.

Hannigan has reached her goal, she said, noting she has been to the "very socially acceptable . . . Radio City Music Hall."

Yes, Mraz can even fill Radio City Music Hall, now that his hit "I'm Yours" has become ours.

David Burger writes about popular music. Contact him at dburger@sltrib.com or 801-257-8620.

Jason Mraz

When » Oct. 28 at 7:30 p.m.

Where » E Center, 3200 S. Decker Lake Drive, West Valley City

Tickets » $26.50 to $32 at ticketmaster.com (325-SEAT)