Unlike the imported Arabian and Thoroughbred, the American Quarter Horse (stock type) is the oldest surviving American horse breed. This horse was developed by the colonists and was often raced down the main streets of early American towns. The Quarter Horse quickly earned the reputation of being the fastest at one-fourth mile, thus leading to its name. The American Quarter Horse was instrumental in settling the West and possessed excellent cow sense for ranch work.

It is believed that the Quarter Horse was influenced by the inclusion of Arabian, Barb, and Turk breeds through a Thoroughbred imported in 1752 named Janus. Most of the foundation Quarter Horse lines trace back to Janus. Later, Peter McCue was foaled in Illinois and is considered to be the most important sire contributing to the development of the Quarter Horse. Nearly 20 percent of the Quarter Horses registered prior to 1948 trace back to him.

The American Quarter Horse has a characteristic short head and sloping shoulder. Powerful muscling is strengthened by a strong, short-coupled body. Quarter Horses are known for their good dispositions and generally stand 14.2 to 15.2 hands tall. Like the Thoroughbred, they, too, have solid coat color patterns.

Speed, athleticism, and versatility are qualities possessed by the American Quarter Horse. Today, the Quarter Horse is used for racing, riding, ranch work, and rodeos.