Secretariat won the 1973 Belmont Stakes by 31 lengths in a time so fast it's never been approached — and when they opened him up after he died, his heart was two and a half times normal size.
Secretariat was a chestnut thoroughbred who in 1973 won the Triple Crown — the Kentucky Derby, Preakness Stakes, and Belmont Stakes — in a manner so dominant it defied rational explanation. He didn't just win; he got faster as each race went on, posting split times in the final quarters that were quicker than his opening quarters. Most horses slow down. Secretariat accelerated.
The 1973 Belmont Stakes is considered the greatest single performance by a racehorse in history. Secretariat won by 31 lengths — a margin so large that the second-place horse was barely visible on television. His time of 2:24 flat for a mile and a half broke the previous record by over two and a half seconds. That record still stands, more than 50 years later, and no horse has come within two seconds of it.
Secretariat appeared simultaneously on the covers of Time, Newsweek, and Sports Illustrated the week after the Belmont — the first athlete of any kind to achieve that. He became a national phenomenon at a moment when America desperately needed one: the Watergate hearings were consuming the country and the Vietnam War was grinding toward its end. A chestnut horse with a blazing stride gave people something uncomplicated to feel good about.
Secretariat was syndicated for a then-record $6.08 million before his three-year-old season, with 32 shares sold at $190,000 each. The agreement required he retire to stud by the end of 1973. He won 16 of 21 career races and earned $1.3 million in prize money — significant at the time, though a fraction of what modern champions earn. His career lasted less than two years.
When Secretariat died in 1989 from a painful hoof disease called laminitis, a necropsy revealed something remarkable: his heart weighed an estimated 22 pounds — roughly two and a half times the average horse's 8.5-pound heart. A larger heart means more blood pumped per beat, more oxygen delivered to muscles, more endurance and speed. No one had known it was that size. It had never been measured. He had won everything he won with an engine almost no one knew existed.
All 19 horses that ran in the 2025 Kentucky Derby were direct descendants of Secretariat through his daughters' bloodlines. He never produced a son to match him — his male offspring were largely ordinary — but his daughters became the mothers and grandmothers of a generation of champions. His influence on thoroughbred racing is incalculable, and his record in the Belmont has outlasted every horse and every era that has tried to break it.