American Pharoah in 2015 was the first triple crown winner since 1978.
There have been 12 triple crow winners in horse racing, with the most recent being American Pharoah in 2015.
Prior to American Pharaoh, the last horse to capture the feat was Affirmed in 1978. Affirmed also capped off the last time there were consecutive years there was a triple crown winner as Seattle Slew won the Kentucky Derby, Preakness Stakes and Belmont Stakes in 1977.
The first horse ton win the three races in the same year was Sir Barton in 1919. The next horse to pull it off was Gallant Fox in 1930.
In 1935, Omaha started a run that last until 1948, in which the most years between triple crown winners was three. War Admiral (1937), Whirlaway (1941), Count Fleet (1943), Assault (1946) and Citation (1948) all completed the task in to create a stretch of six triple crown winners in just 14 years.
The most famous triple crown winner was Secretariat in 1973. The 24 years between Secretariat and Citation is the second longest drought in triple crown history.