.The word "Mustang" comes from the Spanish
word, mesteno, meaning "stray or ownerless" horse. This term
aptly describes all wild horses in the United States. They
descend from horses brought to the Americas by the Spanish.
Although there are several specific mustang breeds, they are
generally maintained in closed environments. The term "American
Mustang" refers to those that freely roam the American west.
In 1971, the United States Congress recognized Mustangs as “living
symbols of the historic and pioneer spirit of the West, which
continue to contribute to the diversity of life forms within the
Nation and enrich the lives of the American people.” Today, Mustang
herds vary in the degree to which they can be traced to original
Iberian horses. Some contain a greater genetic mixture of ranch
stock and more recent breed releases, others are relatively
unchanged from the original Iberian stock, most strongly represented
in the most isolated populations.
Today there are fewer than 25,000 free-roaming
mustangs. More than half of them are in Nevada and there are
significant populations in Montana and Oregon. A few hundred
survive in Alberta and British Columbia, Canada.