American Pharoah is the first Triple Crown winner since 1978.
The thoroughbred won the Belmont Stakes on Saturday, weeks after winning the Kentucky Derby and Preakness Stakes.
Trained by Bob Baffert and ridden by Victor Espinoza, the Kentucky-bred American Pharoah joins 12 other horses as the winner of one of the most elusive achievements in sports. The last Triple Crown winner was Affirmed--37 years ago.
The horse is owned by Ahmed Zayat.
Earlier Saturday, Mayor Greg Fischer's office said a celebration of the Triple Crown winner will be held at the Big Four Bridge at Waterfront Park. A "special light show" is planned on the bridge at 9:04 p.m., the mayor's office said in a news release.