Blazing fast over short distances, the American Quarter Horse has been clocked at speeds of up to 55 mph (88.5 km/h) in races of a quarter mile or less. Known for his versatility, good temperament, and “cow sense,” the Quarter Horse is the most popular breed in the world, with more than four million horses registered. Bred in the early 17 th century in the Virginia and Seaboard settlements from stock of Spanish origin, compact, heavily-muscled, and intelligent, this versatile horse is synonymous with Western riding.