For the third time in seven years, the Kentucky Derby winner will not run in Preakness Stakes, bringing up the question of whether the races should be spread out.

Thirteen horses have won the Triple Crown in American Thoroughbred racing history. Here's a look at the winners and the history of the Triple Crown:

Should the Triple Crown schedule change to give horses time to rest for the Preakness Stakes? 1/ST Racing President Aidan Butler says yes.