Why is the Kentucky Derby only for 3-year-old horses?

May 05, 2017

The Kentucky Derby is coming up soon, and will likely again feature a seemingly endless variety of oddly fascinating women’s hats, but only 3-year-old Thoroughbred racehorses.

Why only 3-year-olds? Why doesn’t arguably the biggest horse race of the year allow the fastest horses to compete against each other, regardless of their age?

Well, the answer to that question seems to be totally unsatisfactory: No one seems to know why. It’s the answer that parents and bosses give when they have nothing else: It’s done that way because it’s the way it’s always been done.

According to an article on the subject, the Kentucky Derby (and Preakness and Belmont) simply carried on the tradition of racing 3-year-olds that began in England: “The predominance of 3-year-olds dates back to the early days of organized English racing. Famous races such as the St. Leger Stakes (first run in 1776), the Epsom Derby (1780), and the Two Thousand Guineas Stakes (1809), which make up the Old World's version of the Triple Crown, have always been limited to 3-year-old entrants. When the comparable American races started up (beginning with the Belmont in 1867), they were closely patterned on their English predecessors…. In keeping with tradition, then, the American races adopted the age restriction, too.”

Why the English decided to race only 3-year-olds in their big races more than 200 years ago has been apparently lost to time. Speculation has been that 3-year-old horses are close to maturity (typically reached at 3.5 to 4 years), although 3-year-olds often have a difficult time when racing against 4-year-olds in such events as the Breeders’ Cup where horses of different ages are allowed to race.

The Kentucky Derby is also a Graded Stakes Race, which is typically restricted to horses that belong to the same gender, age or class.

So, again, no one seems to know why, but it’s the way it’s always been, and the way it will likely always be.