NEW YORK — The Triple Crown trail ends with the Belmont Stakes, and it's finished in heartbreak for 13 horses whose Triple tries were foiled since 1979.

That year Spectacular Bid stepped on a safety pin in his barn and came up short in the Belmont. Big Brown didn't finish the grueling race in 2008; and I'll Have Another was scratched the day before with a leg injury in 2012.

Not since Affirmed in 1978 has a horse swept the Triple Crown, one of the sporting world's rarest feats.

American Pharoah began his bid with a one-length victory in the 1 1/4-mile Kentucky Derby on May 2. He followed it up with a seven-length win in the rain-drenched 1 3/16-mile Preakness on May 16.

He'll try to become the 12th Triple Crown winner, joining such revered horses as Whirlaway, Count Fleet, Citation and Secretariat, when he runs in the Belmont on Saturday.

The forecast calls for a 30 percent chance of morning showers with a high in the mid-to-upper 70s at the scheduled post of 6:50 p.m. ET. A crowd capped at 90,000 is expected for a chance to witness history.

Here are some things to know for the 147th Belmont Stakes:

RESTED RIVALS

American Pharoah will be the only horse to run in all three Triple Crown races over a span of five weeks. Five of his rivals competed in the Derby and have been resting ever since. Tale of Verve skipped the Derby and finished second in the Preakness three weeks ago. Madefromlucky is the freshest horse of all; he's been off since winning the Peter Pan Stakes over the same Belmont dirt on May 9. Frosted finished second in his only previous race at Belmont Park, and he trains there. So do Madefromlucky and Materiality, both overseen by Todd Pletcher.

SO MUCH FOR FAVORITES

Being the betting favorite in the Belmont has been more of a curse. The last odds-on favorite to win was Affirmed in 1978. California Chrome was the last odds-on favorite in the race, and he ended up fourth last year. American Pharoah, winner of six straight races, is the early 3-5 favorite, and thousands of sentimental fans figure to snatch up souvenir $2 win tickets.

DAUNTING DISTANCE

At 1 1/2 miles, the Belmont is the longest of the Triple Crown races. It's an odd distance in North American racing; these 3-year-old colts have never been asked to run that far and few will again. Often times, the final quarter-mile is what does in a contender. Once the horses come charging out of the final turn, they face a 1,097-yard run through the stretch, a daunting task for a horse with little or no gas left in the tank. "He doesn't know he's going to go that extra distance, so we'll surprise him," said Bob Baffert, who trains American Pharoah. The track's deep, sandy surface can prove tiring, too. If enough rain falls and turns it into something resembling creamy peanut butter, give the edge to American Pharoah, who has two wins over sloppy tracks. Materiality has one win on a sloppy surface, while Madefromlucky has a second.

RUNNING STYLE

American Pharoah's preferred running style is at or just off the pace, although he can come from behind, too. He was never worse than third in the Kentucky Derby before rallying in the stretch, and he led the entire way in the Preakness despite a deluge of rain that began as the horses were going to the starting gate. In two of his other career starts, he also led the entire way. American Pharoah has awed observers with his fluid and athletic stride, in which he appears to float over the ground.

LUCKY 7

No Triple Crown winner has faced more than seven rivals in the Belmont, and that's how many American Pharoah will take on. Frosted was fourth in the Derby; Materiality sixth; Keen Ice seventh; Mubtaahij eighth; and Frammento 11th. Tale of Verve was a surprising second in the Preakness after skipping the Derby. Madefromlucky skipped the first two races.