<P> Horses in the United States have significant popularity and status that is acknowledged by a number of observers and researchers . There are about 9.2 million horses in the country and 4.6 million citizens are involved in the horse business . In addition, there are about 33,000 feral horses that roam freely in a wild state in certain parts of the country . </P> <P> The horse evolved in the Americas, but became extinct between 8,000 and 12,000 years ago . When the Spanish arrived on the American mainland in the 16th century, they brought horses with them and re-established the animals on the continent . </P> <P> Fossils of the earliest direct ancestor to the modern horse, Eohippus have been found in the Eocene layers of North American strata, mainly in the Wind River basin in Wyoming . Fossils found at the Hagerman Fossil Beds in Idaho, called the Hagerman horse or Equus simplicidens are from the Pliocene, dating to about 3.5 million years ago (mya). Paleontologists determined the fossils represented the oldest remains of the genus Equus . The genus Equus, which includes all extant equines, was plentiful in North America and spread into the Old World by about 2.5 mya . </P> <P> A 2005 genetic study of fossils found evidence for three genetically divergent equid lineages in Pleistocene North and South America . Recent studies suggest all North American fossils of caballine - type horses, including both the domesticated horse and Przewalski's horse, belong to the same species: E. ferus . Remains attributed to a variety of species and lumped as New World stilt - legged horses probably all belong to a second closely related species that was endemic to North America . Digs in western Canada have unearthed clear evidence horses existed in North America as recently as 12,000 years ago . Other studies produced evidence that horses in the Americas existed until 8,000--10,000 years ago . </P>

When did horses first come to north america
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