In the United States, a horse who wins the Kentucky Derby, the Preakness Stakes and the Belmont Stakes. Since most horses are born in the spring, they will be barely three years old and have less than one year of race experience (usually just a handful of starts) before the Derby. For a young, inexperienced horse, running over a mile at top speed can be very difficult, and to do it three times in five weeks has proven almost impossible. In addition, the Triple Crown races are only open to three year olds so each horse has just one chance.

Between 1988 and 1995, a bonus of five million dollars, called the Triple Crown Challenge, was offered to the winner of the three races by Chrysler Corporation. Between 1996 and 2005, the bonus was offered by VISA, but no horse was able to claim it. For 37 years, there were only eleven Triple Crown champions in history, until American Pharoah won the twelfth crown in 2015. Then Justify did it in 2018. More commonly, a horse wins two out of three races. The various race distances contribute: good sprinters may win the shorter contests but tire in the 1 1/2 mile Belmont. Conversely, horses with plenty of endurance might not have the quick speed needed to win the 1 3/16 mile Preakness. In this extremely competitive industry, it takes an all-around champion horse to add a name to the list of Triple Crown winners.

Winners of the Triple Crown: