American Wild Horse History

The Surprising History of America’s Wild Horses

Jay F. Kirkpatrick and Patricia M. Fazio

Modern horses, zebras, and asses belong to the genus Equus, the only surviving genus in a once diverse family, the Equidae. Based on fossil records, the genus appears to have originated in North America about 4 million years ago and spread to Eurasia (presumably by crossing the Bering land bridge) 2 to 3 million years ago. Following that original emigration, there were additional westward migrations to Asia and return migrations back to North America, as well as several extinctions of Equus species in North America.

The last prehistoric North American horses died out between 13,000 and 11,000 years ago, at the end of the Pleistocene, but by then Equus had spread to Asia, Europe, and Africa.

Animals that on paleontological grounds could be recognized as subspecies of the modern horse originated in North America between 1 million and 2 million years ago. When Linnaeus coined the species name, E. caballus, however, he only had the domesticated animal in mind. Its closest wild ancestor may have been the tarpan, often classified as E. ferus; there is no evidence, though, that the tarpan was a different species. In any case the domesticated horse probably did not arise at a single place and time, but was bred from several wild varieties by Eurasian herders.

Additional information on the history of horses:

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Most of the evolutionary development of the horse (54 million years ago to about 10,000 years ago) actually took place in North America, where they developed the very successful strategy of grazing (eating grass) rather than browsing (eating softer succulent leaves). These grazers had evolved specialized teeth for processing the stiff and coarse grass that was at that time becoming very plentiful on the Great Plains of North America. Pliohippus, the first primitive horse that had a single toe and hoof on each leg, like our modern horses.

Horses (Equus) continued to evolve and develop for another six million years after Pliohippus and became very successful, spreading throughout North America. At some point some of them crossed into the Old World via the Arctic-Asia land bridge. Then, suddenly, no one is absolutely certain why, between 10,000 and 8,000 years ago, Equusdisappeared from North and South America. Various theories have been advanced including destruction by drought, disease, or extinction as a result of hunting by growing human populations. At any rate, the horse was gone from the western hemisphere. The submergence of the Bering land bridge prevented any return migration from the Old World or Asia, and the horse was not seen again on its native continent until the Spanish explorers brought horses by ship in the sixteenth century.


The American Mustang is more accurately termed the “feral horse”. Feral horses (commonly known as Mustangs) are those horses whose ancestors were domestic horses that were freed or escaped from early explorers, native tribes, ranches, cavalry, etc. to become free-roaming herds all across the United States. The first domestic horses in America arrived with Columbus on his second voyage in 1493. During the early Spanish exploration years, horses came over with each voyage. The Spanish explorers were supplied these horses by breeding farms in the West Indies. It is not well documented on how or when the first horses were either stolen or escaped from the Spaniards, but it is estimated that by the 1800’s there were 2 to 5 million head of feral horses, mostly in the Southwest. Currently there are only an estimated 29,000 Mustangs still free-roaming on public lands in the states of Arizona, California, Colorado, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, and Wyoming. These numbers were provided by the Bureau of Land Management’s herd statistics. The BLM’s concludes that there is still an excess of about 2,500 horses. Interestingly, there are 32,000 wild horses in BLM holding facilities – more than there are in the wild.

Throughout the history of the feral horse, the government devised ways to reduce the numbers of free-roaming horses to appease the cattle-ranchers vying for the grazing land, and to keep the herds from over-populating thus starving to death due to lack of grazing land. As recently as 1952 a group of concerned citizens in Storey County, Nevada protested in court against roundups of the wild horses to be sent for slaughter by the use of airplanes. They convinced the Board of Commissioners that the practice was inhumane. The use of planes for pursuit of wild horses was banned in Storey County. This was the beginning of the movement to protect wild horses and burros.

“Wild Horse Annie” continued to fight for the survival of the wild horse and burro. She brought the plight of the wild horse and burro to the attention of the U.S. Congress. She lobbied against the cruel capture practices, and for management of the herd reductions so as not to wipe out the wild herds altogether. In 1971 the Wild Free-roaming Horse and Burro Act was passed by Congress which requires the protection, management, and control of wild free-roaming horses and burros on public lands.