What is the Triple Crown in horse racing?

The Triple Crown is one of the most storied achievements in U.S. racing, having been achieved only 13 times in nearly 150 years.
Winning the Triple Crown requires a 3-year-old thoroughbred to capture the Kentucky Derby, Preakness Stakes and Belmont Stakes. The races, which vary in length from the 1 3/16th-mile Preakness to the 1½-mile Belmont, are run over seven weeks at three different tracks – Churchill Downs in Louisville, Kentucky; Pimlico Race Course in Baltimore, Maryland; and Belmont Park on New York’s Long Island.
The feat was first accomplished by Sir Barton in 1919, but the term Triple Crown didn’t come into common usage until 1933, when 1930, when Daily Racing Form columnist Charles Hatton popularized it.
The other Triple Crown winners after Sir Barton are: Gallant Fox (1930); Omaha (1935); War Admiral (1937); Whirlaway (1941); Count Fleet (1943); Assault (1946); Citation (1948); Secretariat (1973); Seattle Slew (1977); Affirmed (1978); American Pharoah (2015); and Justify (2018).
Trainers “Sunny” Jim Fitzsimmons and Bob Baffert and jockey Eddie Arcaro are the only humans to ever participate in two Triple Crown campaigns.