NEW YORK >> Justify led all the way to win the Belmont Stakes by 1¾ lengths today and become horse racing’s 13th Triple Crown champion and second in four years.

The chestnut colt became the second undefeated horse to sweep the Kentucky Derby, Preakness and Belmont, improving to 6-0 in a racing career that began on Feb. 18. Seattle Slew was unbeaten when he won the Triple Crown in 1977.

Sent off as the 4-5 favorite, Justify went to the lead out of the starting gate and led nine rivals around the track’s sweeping turns. He’s the first Triple Crown winner to face that many rivals in the 1½-mile Belmont.

Bob Baffert became the second trainer to win the Triple Crown twice. He did so with American Pharoah in 2015, ending a 37-year drought.

At 52, Mike Smith is the oldest jockey to win the Triple Crown.

Justify ran the longest race of the series in 2:28.18 and paid $3.60, $3.50 and $2.80.

Baffert had fretted after Justify drew the No. 1 post, a spot he detests for his horses. But Smith turned it into an advantage, gunning Justify to the lead and defying any horse to challenge. Restoring Hope, also trained by Baffert, ran interference for the champion while traveling second and deterring any threats by forcing them to go extremely wide. Nobody did.

Smith got the big colt into a relaxed rhythm under a moderate pace heading into the backstretch, and he had an easy trip from there.

There were mild bids turning for home. Vino Rosso made the most serious move to get within a length but never threatened. Justify pulled away down the 1,097-yard stretch in front of a grandstand packed with screaming fans with only 24-1 shot Gronkowski picking up the chase down the lane.

Gronkowski, named for and partly owned by the New England Patriots tight end Rob Gronkowski, returned $13.80 and $7.

Hofburg paid $3.70 to show.