No horse has won the Triple Crown since Affirmed accomplished the feat in 1978.
Since 1978, 13 horses have entered the Belmont Stakes after winning the first two legs of the Triple Crown. Each of those horses has failed to win the final race.
After winning the Kentucky Derby and Preakness, American Pharoah is entering Saturday's race as the clear favorite to win this year's Belmont Stakes. American Pharoah was 1-5 to win the 1.5-mile race when wagering opened on Friday.
Last year, California Chrome won the Kentucky Derby and Preakness before failing to win the Belmont.
California Chrome (2014)
California Chrome was on the cusp of history after winning the Kentucky Derby and the Preakness. At the Belmont, the horse stayed near the top of the pack, but starting falling off after about a half mile.
California Chrome ended up tied for fourth place at the 2014 Belmont Stakes. Tonalist won the race.
After the race, California Chrome's owner Steve Coburn looked straight into the camera and ranted about Chrome losing to a horse that did not participate in the Kentucky Derby or the Preakness.
I'll Have Another (2012)
Unlike the other horses on this list, I'll Have Another never had a chance to win the Belmont Stakes because he never ran in the race.
The day before the race, I'll Have Another's trainer, Doug O'Neill, announced the horse had a front left tendon injury. He never raced again. Without the Triple Crown candidate in the field, Union Rags won the 2012 Belmont Stakes.
Big Brown (2008)
Big Brown made history in the 2008 Belmont Stakes, but not the kind jockey Kent Desormeaux was hoping to make. The horse became the first Triple Crown hopeful to finish in last place at the Belmont. Before the race, Big Brown's cracked hoof injury generated a lot of discussion, but trainer Rick Dutrow described the injury as "just a little hiccup."
Da' Tara ended up winning the 2008 Belmont while jockey Desormeaux eased the injured Big Brown, who did not finish the race.
Smarty Jones (2004)
Smarty Jones' chase for the Triple Crown is one of the most memorable. For the third straight year, a horse entered the Belmont Stakes with a shot at the Triple Crown.
At the Belmont, Smarty Jones raced ahead and even had a four-length lead at one point.
But as Smarty Jones entered the stretch, the lead eventually diminished. Birdstone and jockey Edgar Prado surged in the last furlong and overcame the deficit. The race famously ended with retired horse racing commentator Tom Durkin disappointedly saying "Birdstone wins the Belmont Stakes" as Smarty Jones' lead slipped away at the end.
This was the second time in three years that a horse jockeyed by Prado defeated a Triple Crown hopeful at Belmont.
Funny Cide (2003)
Funny Cide was able to hold off Empire Maker in the 2003 Kentucky Derby, but was unable to do so in that year's Belmont.
With the Triple Crown in sight, Funny Cide had a lead after three-quarters of the race. The horse was unable to maintain the lead, finishing third.
War Emblem (2002)
War Emblem needed to overcome a huge deficit from the beginning after a slow start out of the gate. The horse was able to obtain the lead for a short period during the race, but that quickly disappeared.
At 70-1 odds, Sarava, jockeyed by Edgar Prado, was able to get breeze past War Emblem and stave off Madaglia d'Oro to win the 2002 Belmont.
Each year from 1997 to 1999, a horse entered the Belmont after having won the Kentucky Derby and Preakness. Although Charismatic failed to win the Triple Crown, what happened after the Belmont was a powerful moment between horse and jockey.
Charismatic was able to gain the lead in the final furlong, but crossed the finish at third place. That was when the horse starting pulling up lame after suffering an apparent leg injury. Jockey Chris Antley began holding up Charismatic's front left leg. Veterinarian Larry Bramlamlage told 30 for 30 that if Antley hadn't reacted so quickly, the horse could have suffered a terminal injury.
Real Quiet (1998)
In an absolute thriller, Real Quiet's Triple Crown dreams were crushed in 1998 in the closest possible finish. Victory Gallop sprinted down the stretch and caught up with Real Quiet at the finish line. Replays showed that Victory Gallop defeated the Triple Crown hopeful by a nose.
Victory Gallop had finished second in the Kentucky Derby and Preakness that year, but was able to get the best of Real Quiet in the final moments of the Belmont.
Silver Charm (1997)
Like several other horses who failed to complete the Triple Crown since 1978, Silver Charm had a lead in the final stretch at Belmont.
Touch Gold stormed past in the final moments of the race and Silver Charm came in second.
Sunday Silence (1989)
Sunday Silence was coming off one of the most exciting Preaknesses ever, where he defeated Easy Goer by a nose. Easy Goer also came in second at the Kentucky Derby, but things would turn out much differently in the Preakness.
With a quarter mile left in the race, Easy Goer left no doubt and stormed to a commanding lead, ultimately beating Sunday Silence by eight lengths.
Like Sunday Silence in 1989, Alysheba was able to win the first two legs before losing to a familiar foe at the Belmont.
After Bet Twice finished second in both the Kentucky Derby and Preakness, the horse managed a resounding 14-length victory over the rest of the field. With the Triple Crown on the line, Alysheba finished in fourth.
Pleasant Colony (1981)
Pleasant Colony's trainer Johnny Campo was confident in his horse's ability. He predicted before the Belmont that his horse was going to win the final leg of horse racing's Triple Crown. As the New York Times noted, Campo made the same prediction for both the Kentucky Derby and the Preakness, and Pleasant Colony won both races.
Campo's prediction of the Belmont did not turn out so well.
Pleasant Colony was last at one point in the race and eventually finished third.
Spectacular Bid (1979)
Spectacular Bid was looking to become the third Triple Crown winner in as many years. Seattle Slew had won it in 1977, and Affirmed won in 1978. With a three-length lead in the latter part of the race, it seemed as if Spectacular Bid was poised to make history.
Sports Illustrated's William Leggett said the Triple Crown hopeful "began to behave to behave like a very fat man trying to run up a very steep hill."
Spectacular Bid placed third, and the long Triple Crown drought began.