It turns out that the 1973 Belmont Stakes was not the last time that Secretariat set a record. Some 47 years later, research has shown that the great thoroughbred holds another distinction that will last until a champion of comparable magnitude comes along.

Secretariat broke a long Triple Crown jinx

Citation earned thoroughbred racing’s Triple Crown for 3-year-olds in 1948 by placing first in the Kentucky Derby, the Preakness, and the Belmont Stakes. Over the next quarter of a century, eight others would win the first two stages but only the last of the bunch finished the job by triumphing at Belmont Park. That champion was Secretariat.

It was apparent early on that Secretariat was championship material. He placed fourth in his 2-year-old debut, then won seven of his last eight starts in 1972 with the only loss coming by disqualification for interference. That got Secretariat named the 1972 Horse of the Year, an honor usually reserved for 3-year-olds, and set the stage for a magnificent follow-up.

Secretariat won all three stages of the Triple Crown in record times. His clocking in the Kentucky Derby, when he became the first champion to break two minutes for 1 ¼ miles, still stands, and his time in the Belmont Stakes remains the American record for ​1 ^½ miles on dirt.

It’s the Belmont that is the enduring memory for racing fans because of the way Secretariat dominated. Already far ahead of the field coming off the final turn, Secretariat kicked into a gear unseen before or since at the end of a long race and won by an astonishing 31 lengths.

The 1973 Triple Crown winner wasn’t undefeated

Sports fans remember Secretariat for his impressive wins in the Triple Crown Races and a world record for 1 1/8 miles at the Marlboro Cup, but “Big Red” wasn’t unbeaten in that magical season. He lost at the Wood Memorial, the Whitney, and the Woodward Stakes, but his resume was so sparkling that a second Horse of the Year honor followed.

By previous agreement, Secretariat was retired after the Triple Crown season and put out to stud. He sired several quality colts, but the real gems were the offspring of the mares he sired. Storm Cat, A.P. Indy, and Chief’s Crown were just a few of the notable performers.

The legend of Secretariat remains strong 50 years after his birth. Disney produced the 2010 movie bearing his name, an honor seldom accorded even great human champions.

But Secretariat has also been honored in another special fashion. In researching the names of American roads named for athletes by cross-referencing census data with Google Maps, ESPN determined that there are 263 streets named for the horse. ESPN said that was far more than for any other animal or human athlete.

Why was Secretariat able to accomplish what others couldn’t achieve?

Secretariat was euthanized in October 1989 at the age of 19 after being afflicted with a painful hoof disease. A veterinarian brought in to do a necropsy examined the thoroughbred’s heart and was astonished.

“We just stood there in stunned silence. We couldn’t believe it. The heart was perfect. There were no problems with it. It was just this huge engine.”

Dr. Thomas Swerczek

Dr. Thomas Swerczek estimated Secretariat’s heart to weigh 22 pounds; the heart of an average horse is approximately 8.5 pounds. Secretariat’s bloodlines have been traced back to Eclipse, a fabled racehorse of the late 18^th century who was also determined to have an unusually large heart.

There is a theory that a genetic condition passed down by distaff bloodlines is responsible for the large hearts of certain colts.