The hit that just won't quit

There are no drums. No keyboards. No big chorus. Two acoustic guitars wrap themselves around a light reggae rhythm and a sunny but vague vocal line about looking into your heart to find love, love, love. The song recalls sun-soaked holidays in the Caribbean and sounds like a demo expertly recorded on the DIY computer program Garageband. The singer himself has admitted: "The first two and a half minutes have so little production you could almost classify it as spoken word."

It is one of the most successful songs of all time. I'm Yours by the Virginia-born singer-songwriter Jason Mraz has been described by the snippy US website The Daily Beast as "the modern-day Rasputin of the Billboard charts - invincible". At time of writing it has spent 72 weeks on the charts, making it the longest-running song on Billboard's Hot 100 in 51 years. But here's the twist: music critics loathe it.

The National contacted writers and editors at Rolling Stone magazine in the US, Q magazine, The Observer Music Monthly, Uncut magazine, The Word magazine and Mojo magazine in the UK and everyone refused to go on the record about the song, so deep was their loathing, so complete their bafflement at its enduring success. "We played it in the office," said one critic, who refused to be named, "and we thought, What is all the fuss about?"

"I don't really know why the US goes for this kind of Jack Johnson, hacky-sack music," said another, again insisting on anonymity so as not to put out of joint the nose of Mraz's record company Atlantic or appear out of step with the listening public. "It's as mystifying to me as Paul Weller probably is to an American." Cultural relativism aside, what is it about I'm Yours that has seen it hang around the Billboard charts since May 2008, taking the record for most enduring hit from LeAnn Rimes' late-1990s smash, How Do I Live, which lasted 69 weeks?

Mraz's tune was nominated for Song of the Year at this year's Grammy Awards and, according to Reuters, has now become the only track to reach No 1 on each of the four radio-based charts: Mainstream Top 40/Pop Songs, Adult Contemporary, Adult Top 40, and Triple A. Why has it also found its way on to charts for Latin Pop and Smooth Jazz? What makes it such a hit? The San Diego based Mraz, who has spent the last two years touring in support of his album We Sing. We Dance. We Steal Things, is as baffled as everyone else. "I don't feel like I crossed a finish line. I don't feel like I've sweated for 70 weeks. I feel like the song is just doing its thing and it was a real gift," he has said.

The song's beachy good vibes are similar to Jack Johnson, the ex-surfer turned recording star who peddled what Mojo called "gap-year spirituality" over acoustic soft rock and reggae, effectively creating along the way the genre for lightweight pop-reggae positivity. While many found Johnson's tunes too anodyne for non-beach listening, he nevertheless enjoyed two No 1 albums in the US, the most recent one last year. In a parallel development, one of the most consistent selling records in the US is Legend - The Best Of Bob Marley And The Wailers - a staple among college students - which regularly shifts around 13,000 copies a year every year. These two facts help explain why America finds Mraz's jaunty reggae strummer so appealing.

"There is a place in the American heart for sunny, up tempo beach music," agrees Q magazine's Mark Blake. "It's probably no coincidence that Jack Johnson does well in New Zealand too. In the UK and elsewhere, beaches aren't quite the same." But, according to the journalist and songwriter Adrian Deevoy, the real reason I'm Yours is so successful is a matter of melodic combination. Or put another way, it's the chords he uses.

"I'm Yours features the chord sequence," says Deevoy. "Dominant, fifth, relative minor, fourth. The same chords have formed the backbone of some massive pop songs. No Woman No Cry (Bob Marley). Don't Think Twice It's Alright (Bob Dylan), So Lonely (The Police), Another Girl, Another Planet (The Only Ones). The chord sequence virtually guarantees a hit. It's amazing more songwriters don't use it." If Mraz's mega-selling hit is anything to go by, it certainly is.