By Steve Keating

TORONTO (Reuters) - March Madness boasts a $10.8 billion TV deal, billions more are bet in office pools and it has the attention of U.S. President Barack Obama, but America's fascination with the college basketball tournament remains a mystery to the rest of the world.

Parked perfectly between the NFL's Super Bowl and the start of the Major League Baseball season, the NCAA tournament is a rite of spring for many Americans that promises weeks of drama and David and Goliath matchups in a ruthless knockout format.

While the mention of March Madness is routinely met with a blank stare outside the United States, it is an obsession with many Americans, including Obama, whose tournament predictions are scrutinized by some as carefully as his foreign policy.

"Most sporting events, products and movies make their way overseas but not this one," Brad Adgate, senior vice president of research at Horizon Media told Reuters. "It's a wonderful process where it just builds to this climax.

"The ratings aren't that much different than the World Series or the NBA Finals and it brings in a very desirable audience ... it's a prestigious sports event and you pay a premium."

Unlike the global following for the Super Bowl, March Madness is a uniquely North American sporting phenomenon where unpaid fresh-faced college players are at the center of a money-spinning colossus.

The players may be classified as amateurs but the business around the NCAA tournament is major league, commanding as much as $1.2 million for a 30-second commercial for the championship game on April 4 in Houston.

With the TV audience increasingly fractionalized, big sport events remain must-see viewing and even prompted CBS and Turner Broadcasting to shell out nearly $11 billion to secure March Madness broadcast rights for 14 years.

Between 2000-2009, network TV advertising has translated into $4.55 billion of spending from more than 280 marketers, according to research from Kantar Media.

Only the NFL playoffs generate more add revenue than March Madness, which last year pulled in $651 million -- more than either the NBA and Major League Baseball playoffs.

Houston will host the NCAA's Final Four from April 2-4 and the local tourist board expects more than 70,000 visitors to pump close to $100 million into the economy.

Each of the 68 schools in the tournament will receive a cut of television money and pocket millions from licensing deals.

"It (March Madness licensing) is up there on the same scale with those (NFL, NBA, NHL, MLB)," Marty Brochstein, senior vice president of the International Licensing Industry Merchandisers' Association told Reuters.

"At each of the (tournament) venues there is merchandise for each of the schools, hats, T-shirts ... It's a big business in those venues."

Millions of Americans have a stake in March Madness filling out their tournament brackets with the same attention to detail they pay to filing their tax returns.

According to a 2010 survey by CareerBuilders.com, 20 percent of U.S. employees participate in a March Madness pool at work with of billions of dollars changing hands.

"It just lends itself to interaction and it also comes at a great time of year ... the timing is right," said Adgate. "It is three weeks where it is the dominant sporting event."

(Editing by Frank Pingue)