 A small number of dedicated breeders preserved the Appaloosa as a distinct breed until the Appaloosa Horse Club (ApHC) was formed as the breed registry in 1938.The modern breed maintains bloodlines tracing to the foundation bloodstock of the registry; its partially open stud book allows the addition of some Thoroughbred, American Quarter Horse and Arabian blood.Today, the Appaloosa is one of the most popular breeds in the United States; it was named the official state horse of Idaho in 1975.