<P> In the United States, the Triple Crown of Thoroughbred Racing, commonly known as the Triple Crown, is a title awarded to a three - year - old Thoroughbred horse who wins the Kentucky Derby, Preakness Stakes, and Belmont Stakes . The three races were inaugurated in different years, the last being the Kentucky Derby in 1875 . These races are now run annually in May and early June of each year . The Triple Crown Trophy, commissioned in 1950 but awarded to all previous winners as well as those after 1950, is awarded to a Triple Crown winner . </P> <P> The first winner of all three Triple Crown races was Sir Barton in 1919 . Some journalists began using the term Triple Crown to refer to the three races as early as 1923, but it was not until Gallant Fox won the three events in 1930 that Charles Hatton of the Daily Racing Form put the term into common use . </P> <P> Only twelve horses have won the Triple Crown: Sir Barton (1919), Gallant Fox (1930), Omaha (1935), War Admiral (1937), Whirlaway (1941), Count Fleet (1943), Assault (1946), Citation (1948), Secretariat (1973), Seattle Slew (1977), Affirmed (1978), and American Pharoah (2015). </P> <P> James E. "Sunny Jim" Fitzsimmons was the only trainer to win the Triple Crown more than once; he trained both Gallant Fox and his son Omaha for the Belair Stud breeding farm . Gallant Fox and Omaha are the only father - son duo to win the Triple Crown . Belair Stud and Calumet Farm are tied as the owners with the most Triple Crown victories with two apiece . Calumet Farms won with Whirlaway and Citation . Eddie Arcaro rode both of Calumet Farms' Triple Crown champions and is the only jockey to win more than one Triple Crown . </P>

What was the last horse to win triple crown