The fastest horse in the world, the American Quarter Horse is a specialized sprinter with a quick turn of foot. Racing at speeds up to 55 mph, Quarter Horses can cover a quarter-mile in less than 21 seconds, starting from a flat-footed standstill. Quarter Horses are traditionally short, stocky horses that are specialized sprinters. Quarter Horse races are measured in yards, and are typically between 220 and 770 yards. The classic distance is 440 yards, which is where the horse originally drew its name.