One of the principal forms of horse racing, which is popular in
many parts of the world, is thoroughbred racing. Harness racing
is also popular in the eastern United States and more popular than
thoroughbred racing in the United Kingdom and Canada. Quarter horse
and Arabian racing are also popular in the western United States.
The breeding, training and racing of horses in many countries is
now a significant economic activity as, to a greater extent, is
the gambling industry which is largely supported by it. Exceptional
horses can win millions of dollars and make millions more by providing
stud services, such as horse breeding.
The style of racing, the distances and the type of events varies
very much by the country in which the race is occurring, and many
countries offer different types of horse races.
In the United States, races can occur on flat surfaces of either
dirt or grass, generally thoroughbred racing; other tracks offer
quarter horse racing and harness racing, or combinations of these
three types of racing. Racing with other breeds, such as Arabian
horse racing, is found on a limited basis. American thoroughbred
races are run at a wide variety of distances, most commonly from
4.5 furlongs (905 m) to 11⁄2 miles (2414 m); with this in
mind, breeders of thoroughbred race horses are able to breed horses
to excel at a particular distance (see Dosage Index).
The high point of US horse racing has traditionally been the Kentucky
Derby which, together with the Preakness Stakes and the Belmont
Stakes, form the Triple Crown for three-year-olds. However, in recent
years the Breeders' Cup races, held at the end of the year, have
been challenging the Triple Crown events, held early in the year,
as determiners of the three-year-old champion. They also have an
important effect on the selection of other annual champions. The
corresponding standard-bred event is the Breeders' Crown. There
are also a Triple Crown of Harness Racing for Pacers and a Triple
Crown of Harness Racing for Trotters.