The American Quarter Horse, or Quarter Horse, is an American breed of horse that excels at sprinting short distances. Its name is derived from its ability to outrun other horse breeds in races of a quarter mile or less; some have been clocked at speeds up to 44 mph (70.8 km/h). The development of the Quarter Horse traces to the 1600s. The American Quarter Horse is the most popular breed in the United States, and the American Quarter Horse Association is the largest breed registry in the world, with almost three million living American Quarter Horses registered in 2014. The American Quarter Horse is well known both as a race horse and for its performance in rodeos, horse shows, and as a working ranch horse. The compact body of the American Quarter Horse is well suited for the intricate and quick maneuvers required in reining, cutting, working cow horse, barrel racing, calf roping, and other western riding events, especially those involving live cattle. The American Quarter Horse is also used in English disciplines, driving, show jumping, dressage, hunting, and many other equestrian activities. Breed history Colonial era In the 1600s on the Eastern seaboard of colonial America, imported English Thoroughbred horses were first bred with assorted native horses. One of the most famous of these early imports was Janus, a Thoroughbred who was the grandson of the Godolphin Arabian. He was foaled in 1746, and imported to colonial Virginia in 1756. The influence of Thoroughbreds like Janus contributed genes crucial to the development of the colonial "Quarter Horse". The resulting horse was small, hardy, quick, and was used as a work horse during the week and a race horse on the weekends. As flat racing became popular with the colonists, the Quarter Horse gained even more popularity as a sprinter over courses that, by necessity, were shorter than the classic racecourses of England. These courses were often no more than a straight stretch of road or flat piece of open land. When competing against a Thoroughbred, local sprinters often won. As the Thoroughbred breed became established in America, many colonial Quarter Horses were included in the original American stud books. This began a long association between the Thoroughbred breed and what would later become officially known as the "Quarter Horse", named after the race distance at which it excelled. Some Quarter Horses have been clocked at up to 44 mph.