trials of speed involving two or more horses. It includes races among harnessed horses with one of two particular gaits, among saddled Thoroughbreds (or, less frequently, quarterhorses) on a flat track, or among saddled horses over a turf course with obstacles to be jumped (steeplechase).
Horse races, today popular throughout most of the Western world as well as in other areas, were probably contested as early as 1500 B.C. in Egypt. The roots of harness racing extend back at least to early Greece, where chariot races were a part of the Olympic games. In the Roman era the chariot race became an entertainment for the masses; the Circus Maximus seated over 200,000 spectators. The constant and widespread desire for faster and stronger horses for work, military use, and sport led to the development of several specially bred strains.
In 12th-century England, Henry II mated the offspring of the speedy Arabian stallions bred in the 9th–11th cent. with his own powerful mares. The resultant breed drew proud owners into informal wagers and races to determine the superior horses and riders. The first public racecourse opened at London about 1174, and the “sport of kings” became a staple of fairs. As early as the 16th cent., prizes were awarded in English racing, but the 12th Earl of Derby originated (1780) the first event held on a sweepstakes basis (whereby the winner “sweeps” the stake offered) at his estate in Epsom; known as the Epsom Derby or English Derby, it continues to be held annually.
In the American colonies, horse racing's appeal was evident in the 17th cent. Informal races, often held on busy roads, gave way by century's end to formal contests at racetracks. Although racing waned during the Revolutionary period, it regained popularity afterward, and in 1823 a North-South challenge drew 60,000 spectators to Long Island's Union Course (N.Y.) for a contest of three four-mile heats between two horses.
Steeplechase (the racing of horses over a course with hurdles and shallow water jumps to approximate country riding conditions) became popular in England and Ireland in the 19th cent. The Grand National Steeplechase, held annually since 1839 at Aintree course, Liverpool, England, is the most famous.
Harness racing, begun in the 1830s from the custom of informal carriage races, became very popular in the 1870s, and in 1891 the modern low-wheel sulky replaced the high-wheeler. Harness racing features two differently gaited standardbred horses—pacers (laterally gaited), which move with a swaying motion, bringing the right front and right hind legs forward at the same time, and trotters (diagonally gaited), which move with a high-stepping, straight ahead gait with left front and right hind legs moving forward in unison. Harness racing, formerly a favorite event mainly at U.S. country fairs, became increasingly popular after World War II at racing centers near urban areas. The United States Trotting Association (formed 1938) governs the sport. Notable harness races include the Hambletonian, the Kentucky Futurity, and the Little Brown Jug.
The first major thoroughbred racing in the United States was at the Saratoga Springs, N.Y., track (1863). Churchill Downs, at Louisville, Ky., opened its flat-racing track in 1875; other thoroughbred tracks soon appeared across the country. At that time, jockeys were often African Americans, but whites forced them from the saddle and effectively denied them riding opportunities until the latter part of the 20th cent., when Latin Americans and women also became some of the top jockeys. The Thoroughbred Racing Associations (founded 1942) is the leading regulatory organization in racing, but state racing commissions oversee racing within their borders. The use and abuse of drugs with racehorses, both for treating and masking pain and enhancing performance, has been a chronic problem in modern horse racing.
Historically the three most important U.S. flat-racing events (all limited to three-year-old horses) have been the Kentucky Derby at Churchill Downs, the Preakness at the Pimlico Race Course in Baltimore, and the Belmont Stakes at Belmont Park, on Long Island near New York City. Together these events are known as the Triple Crown, and such winners of all three as Citation (1948) and Secretariat (1973) are considered among the greatest horses in all racing. Since 1984 they have shared the limelight with the annual Breeder's Cup championship, a one-day event comprising seven races of differing conditions held at a premier course. Other important thoroughbred races include the St. Leger Stakes (Great Britain), Queen's Plate (Canada), Melbourne Cup (Australia), Gran Premio Carlos Pellegrini (Argentina), Japan Derby, Prix de l'Arc de Triomphe (France), Preis von Europa (Germany), and Dubai Classic (United Arab Emirates).
Gambling has accompanied horse racing from the beginning, and persists despite attacks by reform groups and religious leaders. In the United States, various states, recognizing an opportunity for increased revenues, began legalizing and taxing betting at the track in the 19th cent. American tracks now use the parimutuel system of wagering, invented in France in the 1860s. All bets are pooled, the odds are based on the relative amounts bet on the horses, and wagering is on whether a horse will win, place (finish second), or show (run third). Some states now also operate facilities for off-track betting (OTB).