On this day in 1973, Secretariat wins the Belmont Stakes to become the first Triple Crown winner since Citation in 1948. Secretariat ran the mile-and-a-half race in 2:24, a world record that many believe will never be broken.

Secretariat, the son of Bold Ruler and Somethingroyal, was raised in Doswell, Virginia, at Meadow Stable by owner Penny Tweedy. He won seven of nine races started as a two-year-old and was the first horse of his age to be named Horse of the Year. After winning the first two races of his three-year-old career, he lost the third, which was also the final tune-up before that year’s Kentucky Derby. Afterward, a painful abscess was found under the horse’s lip, which supporters hoped was the reason for his unexpectedly slow performance. Secretariat did not disappoint at the 1973 Kentucky Derby, where he set a track record of just over 1:59 to beat Sham by two-and-a-half lengths. Secretariat then won the Preakness, and though unofficial timers and spectators insisted the horse had also set a new record there, the official time keeper clocked Secretariat a few seconds slower.

Secretariat came into the Belmont Stakes in Long Island, New York, at 1-to-10 odds, making him the overwhelming favorite. Secretariat’s jockey Ron Turcotte, however, expected a close race with Sham at the longer Belmont. At the beginning of the race, Sham and jockey Laffit Pincay kept pace with the so-called “super horse” but expended too much energy in the process and eventually faded to last place, while Secretariat pulled away from the pack. Secretariat crossed the finish line an amazing 31 lengths ahead of My Gallant and Twice a Prince in a show of speed and endurance horse enthusiasts had never seen. Turcotte later said of the race, “I know this sounds crazy, but the horse did it by himself. I was along for the ride.”

Years later, Secretariat’s dominance as a race horse was attributed to the size of his heart, which was found to weigh 22 pounds, more than twice that of a typical thoroughbred.