By Kristen Johanson

PHILADELPHIA (CBS)American Pharaoh joins the select group of racing horses that have won the Triple Crown, and it only took 37 years. But why is it so difficult for a horse to win all three races?

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In 2004, Philadelphia favorite Smarty Jones was a contender to win the Triple Crown, but lost during the third leg at the Belmont Stakes.

“When the failed, it tugged at the heart-strings of racing fans who were just so desperate for a Triple Crown,” says horse racing expert Steve Ross.

Ross says there is a reason why only twelve horses in history won the title:

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“The Kentucky Derby is a mile-and-a-quarter, the Preakness is 1/16 shorter — a mile and 3/16ths — and then the most daunting is the Belmont, which is a mile-and-a-half. That’s what makes it so difficult to win all three races in that short period of time. ”

Only three-year-old horses compete for the title, after which, they will continue to race in smaller derbies, or enjoy a more, relaxing lifestyle.

“Smarty Jones is now in the bluegrass state of Kentucky, making love to a lot of high class mares and hopefully we will have a lot of Smarties coming to the races,” Ross says.

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He adds the newest Triple Crown champion injects enthusiasm back into the industry.