The racehorse Secretariat, of Meadow Stables (racing colors pictured), won the Belmont Stakes by 31 lengths, achieving the first American Triple Crown victory in a quarter of a century.

Secretariat, also known as Big Red, was a champion American thoroughbred racehorse who was the ninth winner of the American Triple Crown, setting and still holding the fastest time record in all three of its constituent races. He became the first Triple Crown winner in 25 years and his record-breaking victory in the Belmont Stakes, which he won by 31 lengths, is often considered the greatest race ever run by a thoroughbred racehorse. During his racing career, he won five Eclipse Awards, including Horse of the Year honors at ages two and three. Widely regarded as one of the greatest racehorses of all time, he was nominated to the National Museum of Racing and Hall of Fame in 1974. In the Blood-Horse magazine List of the Top 100 U.S. Racehorses of the 20th Century, Secretariat was second to Man o' War.

The 1973 Belmont Stakes was the 105th running of the Belmont Stakes at Belmont Park in Elmont, New York, held on June 9, 1973. Facing a field of five horses, Secretariat won by 31 lengths going away, the largest margin of victory in Belmont history, in front of a crowd of 69,138 spectators. His winning time of 2 minutes and 24 seconds still stands as the American record for a mile and a half on dirt. The event was televised and broadcast over the radio.

A horse length, or simply length, is a unit of measurement for the length of a horse from nose to tail, approximately 8 feet (2.4 m).

In the United States, the Triple Crown of Thoroughbred Racing, commonly known as the Triple Crown, is a series of horse races for three-year-old Thoroughbreds, consisting of the Kentucky Derby, Preakness Stakes, and Belmont Stakes. The three races were inaugurated in different years, the last being the Kentucky Derby in 1875. The Triple Crown Trophy, commissioned in 1950 but awarded to all previous winners as well as those after 1950, is awarded to a horse who wins all three races and is thereafter designated as a Triple Crown winner. The races are traditionally run in May and early June of each year, although global events have resulted in schedule adjustments, such as in 1945 and 2020.