The American Miniature Horse extracted from many sources in the creation of the breed. The first mention of a small horse being imported into the United States was in 1888; and research shows little public awareness of true Miniatures until 1960. Popular belief is that American Miniature Horses utilized the blood of English and Dutch mine horses brought into this country in the 19th century and used in some Appalachian coal mines as late as 1950.  It also drew upon the blood of the Shetland pony, several of which appear in the pedigrees of some miniatures today. In the past decade, several breeders have imported miniature horses from England, Holland, Belgium, and West Germany, while others have selectively bred miniatures from the larger breeds of horses. Throughout its colorful past, the Miniature Horse breed has been bred for pets, novelty, research, monetary gain, mining work, exhibition and royal gifts.

    The American Miniature Horse Registry (AMHR) is the oldest registry and sanctioning body for Miniature Horses in the United States. The AMHR was created in 1971 to sanction, register and promote the most diminutive animals in the equine industry. In 1971, a group of Miniature breeders approached the American Shetland Pony Club to request that the ASPC open up a registry division for the Miniature. At this meeting at the ASPC office in West Lafayette, Indiana, the American Miniature Horse Registry was born. In December 1971, The Pony Journal announced the creation of the American Miniature Horse Registry and Stud Book. The term American Miniature Horse was also defined in the early rules set by the first AMHR committee. In rules that appeared in The Pony Journal, "The American Miniature Horse shall be, as the name implies, an unusually small equine, not exceeding 34" (inches) in height at maturity. It shall be perfect in form and normal in function, with head, body and legs presenting a pleasing, well-proportioned appearance." The first horse was registered in the AMHR in January 1972 by Russell Jackson of Owensburg, Indiana, #001P Mini Pony Tony. All foundation stock had to be foaled before December 31, 1971. Following the closing of the registry on December 31, 1973, the only animals eligible for registration were those produced by crosses of registered stock.
By the mid 1980s there were more shows and more profound growth. This growth may ultimately have let to addition of the "B" Division for the Miniature Horse. At the 1986 ASPC convention in Williamsburg, Virginia, the "B" division was added for horses 34" to 38". The first Miniature registered in the B Division was Tinkerville Hobby, a 37.5" red chestnut stallion owned by Jean Hatch. The horse was registered on December 22, 1986. Since the late 80s, the AMHR has experienced growth while the Miniature Horse has experienced ever-growing popularity.

    The American Miniature Horse Association (AMHA) was organized and incorporated in July of 1978 to maintain a registry and stud-book. It is now the only registry in existence that deals exclusively with true Miniatures, 34 inches and under. Ponies over 34 inches are not considered Miniatures; they were not in the beginning, and they are not today (excluding the AMHR miniatures that measure 38 inches and under).

     The American Miniature Horse as a breed is currently being standardized. A Standard of Perfection was adopted in 1978 and that two basic body types, a "draft" type and a fine-boned "refined" type, were present in the existing foundation stock, the Standard called for a blending of types into an elegant little horse.