"While genus Equus, of which the horse is a member, originally evolved in North America, these horse relatives became extinct on the continent approximately 8,000–12,000 years ago. In 1493, on Christopher Columbus' second voyage to the Americas, Spanish horses, representing E. caballus, were brought back to North America, first to the Virgin Islands; they were introduced to the continental mainland by Hernán Cortés in 1519. From early Spanish imports to Mexico and Florida, horses moved north, supplemented by later imports to the east and west coasts brought by British, French, and other European colonists. Native peoples of the Americas quickly obtained horses and developed their own horse culture.[5][6]"
"While genus Equus, of which the horse is a member, originally evolved in North America, these horse relatives became extinct on the continent approximately 8,000–12,000 years ago. In 1493, on Christopher Columbus' second voyage to the Americas, Spanish horses, representing E. caballus, were brought back to North America, first to the Virgin Islands; they were introduced to the continental mainland by Hernán Cortés in 1519. From early Spanish imports to Mexico and Florida, horses moved north, supplemented by later imports to the east and west coasts brought by British, French, and other European colonists. Native peoples of the Americas quickly obtained horses and developed their own horse culture.[5][6]"
Source: https://en.wikipedia.org/wiki/Horses_in_the_United_States