From page 432 in Horses of the World:
A great equestrian nation, the United States has a large number of breeds, among the most famous and admired. It also has the greatest number of horses of any country in the world; in 2011 around 10,150,000 horses were counted (with Texas in the lead, followed by California, Florida, and Oklahoma). The United States has favored the breeding of horses with excellent character, with a great diversity of coat colors, and with supplemental gaits that are encouraged or developed in many breeds.
Today, we’re bringing you 5 fun facts about America’s most popular horse—the Quarter Horse:
1. The Quarter Horse is an incredible sprinter and is the fastest in the world over quarter-mile courses, 440 yards (around 402 m), from which it derives its name (it was first called the Quarter Running Horse).
2. The Quarter Horse, one of the oldest of American breeds, descends from Iberian and Eastern horses, crossed with the ancestors of English Thoroughbreds.
3. The Quarter Horse has a particularly docile nature, is cooperative, adaptable, calm, and reliable following many years of selection for good character.
4. The Quarter Horse excels in Western riding (reining, trail, cutting, and others), its specialty, but it also makes a good carriage horse and is used for trekking, racing, polo, and so forth. Its excellent, reassuring character makes it good for beginning riders.
5. The breed is the most popular in the world, and it is very widespread with around 5 million horses registered with the American Quarter Horse Association.
Horses of the World is a comprehensive, large-format overview of 570 breeds of domestic and extant wild horses, including hybrids between the two and between domestic breeds and other equids, such as zebras. This beautifully illustrated and detailed guide covers the origins of modern horses, anatomy and physiology, variation in breeds, and modern equestrian practices. The treatment of breeds is organized by country within broader geographical regions—from Eurasia through Australasia and to the Americas. Each account provides measurements (weight and height), distribution, origins and history, character and attributes, uses, and current status. Every breed is accompanied by superb color drawings—600 in total—and color photographs can be found throughout the book.
Describing and depicting every horse breed in existence, Horses of the World will be treasured by all who are interested in these gorgeous animals.