Mustangs are descended from horses brought to North America by Spanish explorers in the 1500s and have been used by both Native Americans and American pioneers for work and transportation. Although many mustangs live in the wild, they are considered feral because they come from domesticated animals.
Today, the mustang is considered a breed of horse in and of itself, but originally, it was not a breed. It was a designation for an ownerless or stray horse. The first strays came from Spanish stock brought over to the Americas. These strays eventually bred with quarter horses, draft horses and thoroughbreds to create a distinct breed. Both Native Americans and pioneers rounded them up for use in the American West because the horses had certain desirable traits like stocky legs, great speed and high stamina. This made them good choices for long journeys and hard work.
Mustangs measure between 56 and 60 inches high and weigh approximately 800 pounds. They live mostly in the western United States on public land, particularly in Utah, Wyoming, Montana, Oregon, California, Arizona, Idaho, Nevada, North Dakota and New Mexico. There are some mustang herds that live on islands just off the East Coast such as Assateague, Cumberland, Sable and Shakleford.